Subjective well-being (SWB) is the degree to which an individual judges the overall quality of her or his life as a whole in a favorable way, consisting of cognitive evaluation and affect experience. It has long been a construct of interest in the field of positive psychology. However the subjective well-being of adolescent did not received enough attention as it should. Previous studies demonstrate that family, peer and individual factors show great impact on adolescent SWB. Yet little is known about the underlying mechanism of how these factors act synergistically on adolescents’ SWB. And the Developmental Contextualism shows the necessity of knowing more about how family, peer and individual factors affect adolescents’ SWB synergistically. Among many influential factors, recent studies have shown that family function as an integrated and deep family variable, peer attachment as a momentous peer variable, prosocial behavior as a reflect variable of individual adapting to the society actively, were positively associated with subjective well-being, and their impact on subjective well-being is not independent of each other. To explore the relationships among family function, peer attachment, prosocial behavior and adolescents’ well-being, a sequential mediation model is proposed in the current study. In this model, the sequential mediation role of peer attachment and prosocial behavior on the relationship between adolescent family function and subjective well-being had been assumed. 2949 adolescents from 8 schools (1312 boys and 1637 girls, Mage=15.51±1.57) were tested with subjective well-being (consisting of Multidimensional Life Satisfaction Scale for Children, revised Chinese version of Positive and Negative Affect), family function (Family Function Overall Rating Scale), peer attachment (Peer Attachment Scale from revised Chinese version of Inventory of Parent and Peer Attachment), prosocial behavior (Prosocal Behavior Measure for Adolescent), and control variables (including gender, age, Responding Desirably Scale, and Family’s Social Economic Status(SES)). The results as follows: (1) Positive correlations were observed among adolescents’ overall family function, peer attachment, prosocial behavior, life satisfaction and positive affect. And all of those variables have negative correlations with negative affect; (2) Structural equation modeling (SEM) indicated that a sequential mediation model was created. After controlling for age, gender, SES, and social desirability, overall family function significantly predicted adolescents’ subjective well-being directly. It also significantly contributed to adolescents’ subjective well-being indirectly by both separate mediate effect and chained mediate effect of peer attachment and prosocial behavior. The current study explored how overall family function, peer attachment and prosocial behavior influence adolescent’ subjective well-being synergistically, and demonstrated that peer attachment and prosocial behavior had a sequential mediation effect on the relationship between family function and adolescent’ subjective well-being, which contributed to a better explanation of the relationship between family function and subjective well-being. The research findings will play a significant role in promoting the level of adolescent’ subjective well-being. Future studies may further employ longitudinal and experimental methods to explore the relationships among those factors.