She served as the second-ranked Vice Premier of China and the highest-ranking incumbent female government official until March 2023.

Sun served as the party chief of the coastal city of Dalian and as the First Secretary of All-China Federation of Trade Unions.

From 2009 to 2014, Sun served in two prominent regional posts, first as the Chinese Communist Party Committee Secretary of Fujian province, then of Tianjin, one of China's four direct-controlled municipalities.

Her tenure in Fujian made her the second female provincial-level party chief since the founding of the People's Republic of China in 1949 (the first was Wan Shaofen).

Between 2014 and 2017, she served as head of the United Front Work Department of the Central Committee of the Chinese Communist Party.

[3] In 1990, Sun was transferred to work in the organs reporting directly to the provincial party leadership, paving the way for further career advancement.

In 2015, Wang Zhengwei, Vice-Chairman of the Chinese People's Political Consultative Conference, was named deputy head of the department, assisting Sun, creating a unique situation where two of the top leaders of the United Front were held by "deputy national leader" ranked figures.

[8] According to The New York Times, Sun Chunlan become a target of Chinese netizens expressing their anger towards the Zero-COVID policy.