Over the past 40 years, the implementation of the family planning policy in China has led to the creation of many only-child families. In the process of modernization and urbanization, it is critical to focus on the intergenerational relationships in only-child families and their associational mechanism on the life satisfaction of middle-aged and elderly parents, which has crucial implications for them staying active and healthy aging. Using the survey data from Chengdu, China, this study analyzed the characteristics of only-child parents' life satisfaction and family intergenerational relationships, and explored the associational mechanism of family intergenerational relationships on only-child parents' life satisfaction in urban families, as well as the possible moderating role of gender. The results indicate that there are gender differences in the life satisfaction of only-child parents in urban families, and men are more satisfied than women. Moreover, parents of sons and daughters differ in life satisfaction from the dual-gender perspective. Parents of daughters are likely to have higher life satisfaction, especially mothers. The only-child families have not moved toward nucleation in urban families, and intergenerational members maintain close contact and provide frequent mutual support to achieve individual and family development. There are significant gender differences in structural, associational, affectual, and functional solidarity among only-child. This study confirms that there are differences in the associational mechanism of family intergenerational relationships on life satisfaction in different dimensions. Affectual solidarity is the most influential factor of life satisfaction. In terms of normative and consensual solidarity, gender plays a moderating role. For men, normative and consensual solidarity is beneficial for improving life satisfaction, but it has an insignificant effect on women. The effects of structural solidarity, association solidarity, and functional solidarity are not significant.
