Objective: The purpose of this study was to examine the effects of preschooler’s temperament on peer play activity, focusing on the mediation of mothers’social interaction parenting behaviors Methods: 1695 mothers of preschoolers completed questionnaires on children’s temperament and peer play behaviors, and mothers’parenting behaviors. Data were analyzed by regression analyses by SPSS 18.0. Results: First, preschoolers' sociability exerted positive effects on good peer play behaviors(play interaction) and negative effects on the bad peer play behaviors (disruption, disconnection) and both were partially mediated by mothers’social in-teraction parenting behaviors. Second, preschoolers' emotionality exerted negative effects on good peer play behaviors and positive effects on the bad peer play behaviors and both were partially mediated by mothers’social interaction parenting behaviors. Preschoolers' activity exerted positive effects on good peer play behav-iors and negative effects on the bad peer play behaviors and both were partially mediated by mothers’social interaction parenting behaviors. Conclusion/Implications: These findings provide preliminary evidence that moth-ers' social interaction parenting behavior partially mediate the effects of pre-schoolers’temperament on peer play behaviors. Implications for the use of inter-vention targeting specific temperament have been discussed.