众多研究表明，流动儿童的心理状态与城市儿童有着不同的特征，其中关注其问题及缺陷的研究较多，关注其积极发展结果的研究较少。本研究同时关注流动儿童的内外化问题及主观幸福感，旨在更全面地了解流动儿童的心理状态，探讨家庭功能及积极青少年发展与内外化问题及主观幸福感之间相互作用关系。 本研究采用横向研究方法，对北京市两所普通公立中学及一所民营流动儿童学校的816名初一初二学生进行问卷调查，其中城市儿童354人（43.4%），流动儿童462人（56.6%），施测后对有效问卷进行编码及录入，并使用SPSS23.0和Mplus7.4进行数据分析。研究得到以下结论： 第一、流动儿童与城市儿童在家庭功能的问题解决、沟通、角色、情感反应、情感介入、行为控制6个维度和家庭一般功能维度，均存在显著差异，流动儿童的家庭功能明显比城市儿童差。在家庭功能的行为控制维度存在性别差异，男生的家庭功能显著比女生差。 第二、流动儿童与城市儿童在积极青少年发展的能力、自信、联结维度存在显著差异，流动儿童组得分低于城市儿童。自信和关心维度存在显著性别差异，男生的自信维度得分显著高于女生，女生关心维度显著高于男生。 第三、流动儿童与城市儿童的积极情感和消极情感体验总分及生活满意度均存在显著差异，流动儿童得分明显低于城市儿童。外化问题及抑郁量表得分均不存在显著差异。 第四、家庭功能各维度与流动儿童积极青少年发展各维度负相关，与内外化问题正相关，与主观幸福感各维度负相关；积极青少年发展与内外化问题负相关，与主观幸福感各维度正相关；内外化问题和主观幸福感各维度负相关。 第五、积极青少年发展在家庭功能与内外化问题及主观幸福感之间的中介效应显著；流动儿童和城市儿童的中介效应模型分组比较无显著差异。 总之，本研究补充了国内对于流动儿童积极青少年发展的实证研究，并探索了积极青少年发展在家庭功能与内外化问题及主观幸福感之间的中介作用。揭示了家庭功能可以通过影响儿童的积极青少年发展水平，从而影响其内外化问题与主观幸福感。为面向流动儿童的心理健康干预工作提供了理论依据。

Many studies have shown that the psychological development of migrant children has different characteristics with urban children, among which there are more researches focused on their problem behavior and less on their positive factors. This study focuses on both the problem behavior and subjective well-being of migrant children. It aims at a more comprehensive understanding of the psychological development mechanism and influencing factors of migrant children. In this study, a questionnaire survey was conducted on 816 primary students in two public middle schools and a private migrant Children school in Beijing. SPSS23.0 and Mplus7.4 were used to analysis the data. The main findings are as follow: First, there are significant differences in all dimensions of family functioning (problem solving, communication, role, emotional response, emotional intervention, behavior control and family general function) between migrant children and urban children. The family functioning of migrant children is significantly worse than that of urban children. There is gender difference in family functioning control dimension, while girls scored significantly lower than boys. Second, there are significant differences in the 3 dimensions of Positive youth development (competence, confidence and connection) between migrant children and urban children. Boys' confidence is significantly higher than girls', and girls' caring are significantly higher than boys'. Third, there are significant differences in positive and negative emotional experience and life satisfaction among migrant children and urban children. There is no significant difference in the external problem behaviors and depression scale. Fourth, family functioning is negatively related to the positive youth development and subjective well-being, positively related to problem behavior. Positive youth development is negatively related to problem behavior, and is positively related to the subjective well-being. Problem behavior and subjective well-being are negatively related to each other. Fifth, the mediating effect of positive youth development between family functioning and Problem behavior/subjective well-being is significant, and there is no significant difference between the mediating effect model of the migrant children and the urban children. In conclusion, this study enriched the domestic empirical study on the positive youth development in migrant children in China, and explored the mediating effect of positive youth development between family functioning, problem behavior and subjective well-being. It is revealed that family functioning could influence children's positive youth development level, thereby affecting their problem behaviors and subjective well-being. It provides a theoretical basis for mental health intervention for migrant children.