我国实施“全面开放二孩”政策以来，关于养育二孩的讨论日益增多，尤其是头胎子女的情绪行为问题。本文选取母亲社会支持视角，了解二胎出生后头胎子女的一般情绪和行为表现，母亲在二孩养育中的情绪状况，家庭中母亲社会支持的情况，特别是父亲参与（教养方式）对母亲情绪的影响，进而如何对头胎子女的情绪行为产生影响的。研究结果将为当前以及未来二孩家庭提供实证依据,为创造一个有利于头胎子女心理健康发展的成长环境提供一定的参考和借鉴。 研究的内容主要包括以下几个方面： 1：文献综述。包括国内外文献中关于头胎子女情绪行为问题的理论依据与实证研究。现有研究的不足及本研究的创新性、意义等。 2：研究方法。在确定了研究目的及研究问题后，本研究以北京及苏州40位二孩母亲为调查对象，通过半结构式访谈的方式开展调查，使用N-vivo对访谈内容进行编码，最后分析数据，撰写报告。 3：研究结果表明：二胎子女出生后，大多数头胎子女的消极情绪行为远远高于积极情绪行为。母亲的积极情绪对于头胎子女在二胎出生后的情绪行为有着正向的预测作用。母亲社会支持（父亲、其他成员）与头胎子女的情绪行为显著相关，一部分直接对头胎子女的情绪行为产生影响，另一部分是通过母亲的情绪对头胎子女的情绪和行为起间接作用。 4：对研究结果及可能的原因进行讨论，并提出教育建议。 5：研究结论。

Since the two-child policy fully liberalized in our country, there has been an increasing number of discussions about how to care for two children, especially the emotion and behavior of the first-born children. This thesis focused on maternal social support, and investigate the following: 1) The emotion and behavior of the first-born child after birth of the second child; 2) The emotion of mother in the two-child parenting; 3) The social support of the mother in the family, especially the influence of the father involvement (parenting style) on the emotion of the mother; 4) Thus how it affects the emotion and behavior of the children of the first-born child. The research results will provide empirical evidence for current and future two-child families and provide some references and examples for creating a beneficial environment for the first-born children to develop their mental health. The main contributions of the study include the following aspects: 1. Literature review. This part includes the theoretical basis and empirical research on the emotion and behavior of the first-born children in domestic and foreign literature. The drawbacks of the existing research and the innovation and significance of this research are presented. 2. Methods. The Objectives and Designs were described. Participants were 40 mothers of two children from Beijing and Suzhou, and the survey was conducted via semi-structured interviews. N-vivo was used for coding, and finally, the data was analyzed and the report was written. 3. Results. The study showed that after the birth of the second child, the negative emotion and behavior of most of the first-born children were much higher than the positive ones. The positive emotions of the mother have a positive correlation on the emotion and behavior of the first child after the birth of the second child. Maternal social support (father, other family members) is significantly related to the emotion and behavior of the first-born children. It can directly affect the first-born children, and also an indirect effect of the mother's emotions on the emotion and behavior of the first-born children. 4. Discussion. The results and possible causes, and propose educational recommendations are analyzed. 5. Conclusions.