Objective: To investigate the mutual prediction relationship between peer relationship and internalizing problem. Methods: One-year follow up survey was conducted with a sample of 220 preschool children from 4 kindergartens in Shandong province. The quality of peer relationship and degree of internalizing problem were evaluated with the Peer Relationship Scale and the Child Behavior Checklist Cross-lagged panel analysis was used for mutual prediction among variables. Results: The quality of preschool children’s peer relationship showed an increasing trend with grade(F=6.40, 4.81, P<0.01), while the degree of internalizing problem showed a downward trend(F=7.65, 5.46, P<0.01). The predictive effect of pre-test peer relationship and internalizing problem on post-test corresponding behaviors were all statistically significant (β=0.56, 0.49, P<0.01). The predictive effect of pre-test peer relationship on post-test internalizing problem was statistically significant(β=-0.19, P<0.05). Conclusion Both peer relationship and internalizing problem has a certain stability across time, and early peer relationship and internalizing problem could predict later corresponding behaviors. Early peer relationship can predict later internalizing problem, while early internalizing problem cannot predict later peer relationship.