This study verified the influence of socioeconomic status on the subjective well-being of the elderly and the mediating effect of social justice. A statistical analysis of 4257 data in the China CGSS 2017 database was carried out. The analysis results show that socioeconomic status and social justice have a positive impact on the subjective well-being of the elderly, and the social justice plays an incomplete intermediary role. Based on the results of the analysis, this study puts forward several suggestions in terms of policy and practice. First, government may gradually increase the level of pension benefits of the elderly, and provide minimum living security. Second, the community should provide amenities for the elderly to settle their life inconveniences. This research will help improve the subjective well-being of the elderly.