As the third-largest SO 2 emitter in the world, China is facing mounting domestic and external pressure to tackle the increasingly serious SO 2 pollution. Figuring out the convergence and persistence of sulfur dioxide (SO 2 ) emissions matters much for environmental policymakers in China. This study mainly utilizes the Fourier quantile unit root test to survey the convergence of the SO 2 emissions per capita in 74 cities of China during the period of December 2014 to June 2019, by conducting five traditional unit root tests and a quantile root unit test as a comparative analysis. The empirical results indicate that the SO 2 emissions per capita in 72 out of 74 cities in China are convergent in the sample period. The results also suggest that the unit root behavior of the SO 2 emissions per capita in these cities is asymmetrically persistent at different quantiles. For the cities with the convergent SO 2 emissions, the government should consider the asymmetric mean-reverting pattern of SO 2 emissions when implementing environmental protection policies at different stages. For Hefei and Nanjing, the local governments need to enact stricter environmental protection policies to control the emission of sulfur dioxide.Keywords: SO 2 emissions per capita; quantile unit root test; Fourier quantile unit root test; mean-reverting property Despite the initial achievement, SO 2 emissions in China still surpass the sum of the members of the Organization for Economic Cooperation and Development (OECD) and the U.S. [1]. According to the statistics in China Statistical Yearbook (2019), by the year 2018, in China's total energy consumption, the share of fossil energy (including coal, crude oil, and natural gas) has remained above 85%, while the share of renewable energy (including hydropower, nuclear power, and wind power) has been below 15%. More specifically, in the year 2018, the consumption of coal represents 59% of the total level of energy consumption in China, which leads to the fact that the SO 2 emissions per capita have continuously increased. As the third-largest SO 2 emitter in the world, China is facing mounting domestic and external pressure to tackle the increasingly serious SO 2 pollution.High SO 2 emission is a tremendous threat to the environment change. It is one of the most important on-going anxieties for both emerging countries and developed countries. As a typical traditional contaminant, SO 2 brings many adverse effects to the human body, such as breathing difficulty, pulmonary edema, eye irritation, asthma attacks, cardiopulmonary diseases [2][3][4]. Meanwhile, SO 2 has considerable negative impacts on the ecological environment. For example, a high concentration of SO 2 will change the potential of hydrogen (pH) value of plants, which will lead to agricultural production reduction and forest death. Wei et al. [5] found that in 899 Chinese counties, the estimated cost of agricultural losses induced by SO 2 air pollution reached USD 1.43 billion. According to the data from the Ministry of Ecology and Envir...