Based on the data of China General Social Survey 2021 (CGSS), the relationship between pension insurance participation, mental health and happiness of young people was analyzed. The results are as follows. Pension insurance participation has a significant positive impact on youth happines. Pension insurance participation has a significant positive effect on the mental health of young people. Mental health plays a partial mediating role between pension participation and happiness. Therefore, focusing on improving the participation rate of youth pension insurance and improving the mental health level of young people will provide strong support for better coping with the increasingly aging phenomenon in the future and making old-age preparation.