Objective To investigate the current situation and influencing factors of social adaptation among preschool children with malignancies, and to provide a basis for preventing their maladaptive outcomes. Method A total of 475 preschool children with malignancies admitted to seven tertiary A hospitals were selected as research objects by convenient sampling method.A multicenter cross-sectional survey was conducted using the Social Adaptation Rating Scale for Children with Leukemia, the General Family Functioning Scale, and the Early Childhood Attachment Relationship Scale to collect relevant data. Result The social adaptation score of preschool children with malignancies were （68.80±8.22）, 42.95% of the children had social maladjustment.Logistic regression analysis showed that age, disease stage, region, recurrence, family coping style, general family functioning, hours of internet use per day for children, and early childhood attachment relationship were the influencing factors of social adaptation among preschool children with malignancies （all P＜0.05）. Conclusion The level of social adaptation of preschool children with malignancies is low, and individual characteristics, disease stage, family factors, etc.are the main influencing factors. It is necessary to re-gularly assess the behavioral and psychological adaptation status of children with malignant tumors, formulate targeted intervention strategies, and help them build a good social adaptation mechanism as soon as possible.