This study analyses the evolving means of China's formal language policy on Putonghua and minority languages from 1986 to 2021. This paper identifies four stages based on the shifting focus between Putonghua and minority languages: status planning of the central government (1986-1990), balance via bilingual policy (1991-2000), strong Putonghua spread at all levels (2001-2011), and Putonghua promotion and minority language preservation (2012-2021). Through descriptive and corpus analysis of a self-constructed language policy database, for each stage, we explore the major means stated in policy documents by analysing keywords to explain policy changes with consideration of social conditions. The results show that China has continuously adjusted its formal language policy according to social changes, and that language planning in this emerging economy has been profoundly influenced by national strategy and government administration.