Social participation competencies is a part of core competencies. To develop students’ social participation competencies refers to the project to develop the necessary qualities and key capacities of students in the life-long sense of development required by society. For teenagers, learning characteristic courses which aimed at cultivating social participation competencies is an important way to enhance the attitude and abilities of social participation. And examining the effectiveness of the courses is the key to cultivate social participation competencies. A high school in Shanghai offers characteristic courses of social participation competencies for the whole school which provides a vivid sample for this study. Therefore, this study adopts the school-based research paradigm and takes a high school in Shanghai as a sample to explore the specific mechanism of emotional experience (quality) and public service motivation between the number of characteristic courses studied (quantity) and social participation competencies. A total of 1115 students participated in this survey. There were 528 males and 587 females. They filled out questionnaires regarding course experience, public service motivation and social participation competencies. All of the measures showed good reliability and validity. Among them, the questionnaire of social participation competencies which covered two questionnaires of altruistic behavior and leadership. We analyzed the second order factors, the results showed that the model fitted well (χ2 /df=11.58，NFI=.87, IFI=.88, CFI=.88, RMSEA=.09). Data were analyzed with SPSS 22.0 and PROCESS. Results showed there was no obvious common methods bias using the confirmatory factor analysis. The Process plug-ins was used to analyze the chain mediating effect of emotional experience and public service motivation. The results indicated that (1) there was a statistically significant positive relationship between the number of characteristic courses studied and emotional experience(r = .08, p < .05), the number of characteristic courses studied and public service motivation(r = .10, p < .05), the number of characteristic courses studied and social participation competencies(r = .19, p < .01). Furthermore, there was a statistically significant positive relationship between emotional experience and public service motivation(r = .37, p < .01), emotional experience and social participation competencies(r = .29, p < .01). In addition, there was a statistically significant positive relationship between public service motivation and social participation competencies(r = .68, p < .01). (2) Emotional experience and public service motivation played a fully mediating role in the relationship between the quantity and social participation competencies. The chain mediating effect accounted for 5.72% of the total effect, 95% CI: [.00, .12]. (3) Academic achievement did not play a moderating role in the chain mediation. These findings suggest that learning characteristic courses can improve students’ social participation competencies. At the same time, emotional experience and public service motivation play an important role in this process. The learning of characteristic courses of social participation competencies requires the accumulation of courses and the mobilization of the deep emotional experience, so as to promote the promotion of public service motivation, and provide the cognitive source, emotional source and power source for the formation of social participation competencies.