China's fast-developing urbanization has promoted a great number of rural families migrating to urban areas. The objective of this study is to address the existing situation of urban migrant parents' parenting for infant and toddlers and the association between co-parental self-efficacy and child developmental outcomes. A sample of 387 parents of rural-urban migrant families in urban China was invited to complete the online questionnaires. Results showed that mothers have higher parenting self-efficacy (PSE) levels than fathers in all measured dimensions, and found an interdependence of their co-PSE predicting child development outcomes. This study revealed that rural-urban migrant families were still following Chinese traditional parenting and attributed mothers to the responsibility for early childcare, although the ensuing modernization and ingress of Western values have greatly influenced urban parents' understandings about parenting. Based on these results, this paper provides implications for intervention approaches to promote PSE among migrant parents with young children.