Flag of China

The national flag of the People's Republic of China, also known as the Five-star Red Flag is a Chinese red field with five golden stars charged at the canton. The design features one large star, with four smaller stars in an arc set off towards the fly. It has been the national flag of China since the foundation of the People's Republic of China on 1 October 1949.
The red represents the Chinese Communist Revolution and the five stars and their relationships to each other represent the unity of the Chinese people under the leadership of the Chinese Communist Party (CCP). The flag was first hoisted by the People's Liberation Army (PLA) on a pole overlooking Beijing's Tiananmen Square on 1 October 1949, at a ceremony proclaiming the establishment of the People's Republic of China.

Early flags

 Flags of the Qing Dynasty
The previous flag of China was the "Yellow Dragon Flag" used by the Qing dynasty — the last imperial dynasty in China's history — from 1865 until the overthrow of the monarchy during the Xinhai Revolution. The flag that was adopted in 1867 was triangular, but the dynasty adopted a rectangular version of the dragon flag in 1889.

Republic of China

旗; qīngtiān báirì qí) designed by Lu Haodong, a martyr of the Xinhai Revolution. He presented his d The canton (upper corner on the hoist side) originated from the "Blue Sky with a White Sun flag" (青天白日esign to represent the revolutionary army at the 

Inauguration of the Society for Regenerating China, an anti-Qing society in Hong Kong, on 21 February 1895. This design was later adopted as the KMT party flag and the Coat of Arms of the Republic of China. The "red Earth" portion was added by Sun Yat-sen in the winter of 1906, bringing the flag to its modern form. According to George Yeo, the then Foreign Minister of Singapore in 2011, in those days, the Blue Sky with a White Sun flag was sewn in the Sun Yat Sen Nanyang Memorial Hall (formerly known as the "Sun Yat Sen Villa") in Singapore by Teo Eng Hock and his wife.
 The drafted design had ten stripes with the flag of the Kuomintang in the canton that resembled the flags of the United States, Malaysia, and Liberia.[citation needed]
During the Wuchang Uprising in 1911 that heralded the Republic, the various revolutionary armies had different flags. Lu Hao-tung's "Blue Sky with a White Sun" flag was used in the provinces of Guangdong, Guangxi, Yunnan, and Guizhou. In Wuhan, a flag with 18 yellow stars was used to represent the 18 administrative divisions at the time. In Shanghai and northern China, a "Five-Colored Flag" (五色旗; wǔ sè qí) (Five Races Under One Union flag) was used of five horizontal stripes representing the five major nationalities of China: the Han (red), the Manchu (yellow), the Mongol (blue), the Hui (white), and the Tibetan (black).[citation needed]
When the government of the Republic of China was established on 1 January 1912, the "Five-Colored Flag" was selected by the provisional Senate as the national flag. The "18-Star Flag" was adopted by the army.
And the modern flag was adopted as a naval ensign.
Sun Yat-sen, however, did not consider the five-colored flag appropriate, reasoning that horizontal order implied a hierarchy or class like that which existed during dynastic times.
After President Yuan Shikai assumed dictatorial powers in 1913 by dissolving the National Assembly and outlawing the KMT, Sun Yat-sen established a government-in-exile in Tokyo and employed the modern flag as the national ROC flag. He continued using this design when the KMT established a rival government in Guangzhou in 1917. 

The modern flag was made the official national flag on 17 December 1928 after the successful Northern Expedition that overthrew the Beijing government, though the Five-Colored Flag still continued to be used by locals in an unofficial capacity. 
One reason for this discrepancy in use was lingering regional biases held by officials and citizens of northern China, who favored the Five-Colored Flag, against southerners such as the Cantonese/Hakka Sun Yat-sen.

During the Second Sino-Japanese War, the invading Japanese established a variety of puppet governments using several flag designs. The "Reform Government", established in March 1938 in Nanjing to consolidate the various puppet governments, employed the Five-Colored Flag.

 When Wang Jingwei was slated to take over the Japanese-installed government in Nanjing in 1940, he demanded to use the modern flag as a means to challenge the authority of the Nationalist Government in Chongqing under Chiang Kai-shek and position himself as the rightful successor to Sun Yat-sen. However, the Japanese preferred the Five-Colored flag. As a compromise, the Japanese suggested adding a triangular yellow pennant on top with the slogan "Peace, Anticommunism, National Construction" (和平反共建國; Hépíng fǎngòng jiàn guó) in black, but this was rejected by Wang. In the end, Wang and the Japanese agreed that the yellow banner was to be used outdoors only until 1943, when the banner was abandoned, leaving two rival governments with the same flag, each claiming to be the legitimate national government of China.

The flag was specified in Article Six of the 1947 Constitution. During the Chinese Civil War (prior to October 1949), the flag system under CCP rule in China was very confusing - institutionally, the rival old government flag was recognized as a legitimate national flag, but was not encouraged to be flown. Communist forces and supporters tended to use the CCP flag, the red flag without a design, the army merit flag, and the official military flag that came later. 

In addition, some regions use the Soviet national flag as a substitute, a practice that is severely reprimanded in official CCP documents.
After the Chinese Civil War in 1949, the ROC government led by Chiang Kai-shek relocated its government and its institutions to the island of Taiwan.
On the mainland, CCP forces of Mao Zedong established the People's Republic of China (PRC) and adopted their own national flag. On 23 October 1954, the National Emblem and National Flag of the Republic of China Act (中華民國國徽國旗法; Zhōnghuá Mínguó guóhuī guóqífǎ) was promulgated by the Legislative Yuan to specify the size, measure, ratio, production, and management of the flag. 

https://en.wikipedia.org/wiki/Flag_of_China