We utilize data from 2017CSS to explore factors related to people’s subjective wellbeing (SWB). Employing statistical analysis software, we test the chain mediation effect among social security, social fairness, social trust, and SWB. The results show that social security has a direct positive effect on people’s SWB (β = 0.481, p <0.001). Social security also indirectly influences people’s SWB through social fairness and social trust. High quality of social security can enhance the degree of social fairness thereby increasing the level of social trust, finally contributing to higher levels of SWB in China. The total effect of SWB explained is 49% in the chain mediation model. Based on the results, contributions and limitations are discussed in this paper.