Purpose: Kunjing children without sufficient parental care (KCw/oSPC) faced great challenges in social interaction. This study aimed to design and implement a school-based group intervention study with a randomized controlled trial to improve the social communication and cooperation of KCw/oSPC and assess its effectiveness. Method: Fifty-seven recruited eligible KCw/oSPC were randomly assigned to the experimental group ( n=24) who participated in four-session training, and the waiting group ( n=33) who did not receive any program intervention. Results: KCw/oSPC in both groups took pre and posttests on social communication and cooperation. Mann–Whitney–Wilcoxon and Wilcoxon Signed Rank test results indicated significant changes of KCw/oSPC in the experimental group with medium-size effects (Cohen's d=0.63 for social communication; Cohen's d=0.56 for cooperation). Conclusion: This intervention study, despite limitations, contributed to informing social work services and intervention studies to promote KCw/oSPC's social communication and cooperation in addition to social well-being in China and worldwide.