In recent years, mental health of homosexuals has attracted much attention from society and academia. Meaning in Life is an excellent indicator of mental health. Meaning in life refers as one’s perception of life value and importance. Individuals who have a high sense of meaning in life can deeply understand their life experience, as well as realize the purpose of their own life. Previous studies have demonstrated that the high prevalence of homosexuals’ problem behavior is derived from the lack of meaning in life. Thus, it is necessary to enhance the homosexuals’ meaning in life. However, recent theories and studies focused more on the effect of social prejudice on homosexuals’ mental health, while few studies examined whether positive psychological trait can improve homosexuals’ mental health. Self-concept clarity refers to the degree to which individuals clearly define their own self-concepts. As an important psychological trait that reduce the impact of social prejudice, self-concept clarity is believed to effectively improve homosexuals’ mental health. In the present study, we aimed to examine the relation between self-concept clarity and meaning in life among young gay men, and investigated the mediating effect of internalized homonegativity and coping self-efficacy between them. 405 young gay men were enrolled by web-based sampling method. All the participants were 16-35 years old, and their self-definitions were homosexuals. Self-concept clarity was assessed with General Self-concept clarity Scale, which contains 12 items. Previous research has indicated that this scale has good reliability and validity. Meaning in Life was assessed with Steger’s Meaning in Life Scale, which consists of two dimensions: the presence of meaning and the search for meaning. In this study, only the dimension of presence of meaning was selected. This dimension contains 5 items. In addition, internalized homonegativity was examined by Internalized Homonegativity Scale originally from Herek, Cogan, Gillis and Glunt. This scale has 8 items. At last, coping self-efficacy was rated by a 13-item Coping Self-efficacy Scale. This scale has 3 dimensions: problem-focused coping self-efficacy, self-efficacy of stopping unpleasant emotions and thoughts , and self-efficacy of getting support from friends. Results indicated that: (1) Self-concept clarity of young gay men was positively correlated with meaning in life. (2) Internalized homonegativity and coping self-efficacy played a chain mediating effect between self-concept clarity and meaning in life. That is, Self-concept clarity affected coping self-efficacy through internalized homonegativity, and then, affected meaning in life through coping self-efficacy. (3) Coping self-efficacy played a mediating role between self-concept clarity and meaning in life. That is, Self-concept clarity can indirectly influence meaning in life through coping self-efficacy. Two important research implications can be obtained from this study. Firstly, self-concept clarity plays a significant role in improving homosexuals’ mental health. Thus, social worker should encourage homosexuals to deeply explore themselves and reflect on their own life experiences. Secondly, although internalized homonegativity is considered as a significant factor to affect homosexuals’ mental health, we should pay more attention to develop homosexuals’ coping skills in order to strengthen their self-efficacy.