Abstract: Urban population agglomeration may affect residents' subjective well-being through scale effect and crowding effect. This research using the data of China Labor-Force Dynamic Survey (CLDS) and the city-level macro data shows that there is an inverted U-shaped relationship between urban population aggregation and residents' subjective well-being, with the inflection point at the curve being 0.6 thousand people per square kilometer. After grouping by differences in individual characteristics, it is found that rural residents and low-skilled laborers can benefit more from urban population gathering. In terms of the heterogeneity of urban characteristics, population aggregation can significantly improve the subjective well-being of the residents in the third-tier cities and economically underdeveloped areas. After replacing the regression model, the proxy variables of the explained variables and the measurement range, the conclusion is still consistent and robust. The analysis of the intermediate mechanism shows that urban population agglomeration has an impact on residents' subjective well-being through changes in personal income and work environment satisfaction, social trust level, commuting time and other paths.

Key words: subjective well-being, population aggregation, individual characteristics, urban characteristics