With the declined marriage rate and postponed average age at first marriage in China, it seems essential to understand young adults’ marital attitudes. Most existing literature has focused on the association between differentiation of self and intimate experience in marital relations, while few studies attempted to deeply explore the links between differentiation of self and marital attitudes of unmarried groups in emerging adulthood. In an era when young adults place more value on romantic love in marriage, their self-efficacy in handling romantic relationships may be another important factor to understand marital attitudes. As unmarried marriageable females are more vulnerable to the social pressures of late marriage, this study mainly examined emerging adult females’ marital attitudes. It was hypothesized that relationship self-efficacy would mediate the association between self-differentiation level and marital attitudes. Data were collected through WeChat and Credamo platform and 168 never-married participants aged 19-29 who had been in at least one romantic relationship were invited to complete the Chinese version of the differentiation of self-inventory scale (C-DSI), Relationship Self-Efficacy Scale (RSES), and the Marital Attitude Scale (MAS). The mediation test was performed by the PROCESS procedure for SPSS version 4.0. The results showed that relationship self-efficacy could partially mediate the relationship between young adult females’ self-differentiation level and their marital attitudes. This study indicated that marital attitudes to some extent could be influenced by young females’ experiences in intimate relationships and their capabilities and confidence in forming and maintaining romantic relationships. The data was collected from the Wechat platform where females were invited to pariticipate in this survey if they meet the inclusion criteria. The data was also collected in Credamo platform. Different from the way collecting data from wechat platform, the author sent 520 short questionnaires to users on the Credamo platform to build a sample database. Of these, 178 users who met the inclusion criteria for this study were placed in the sample database . Subsequently, the author sent out formal questionnaires to 178 users in the sample database, and finally received 100 valid questionnaires.