Abstract: Objective To know the social emotional development of toddler and explore the influence of maternal emotion and psychological status on toddler's social emotional development situation. Methods Take random samples (toddler of 12 to 36 months whose major caretaker in family is mother) from two separate communities based in Dalian. Children's mothers were asked to fill in three questionnaires:Toddler Social-emotional Assessment, Background Questionnaire of Children and Symptom Checklist 90. Statistical methods were used to analyze collected data to seek how mothers' emotional and psychological status makes a difference to their children's inner development. Results Fifty children's positive rates from four dimensions (externalizing, internalizing, deregulation and competence) were 24%, 14%, 20% and 22% respectively. 52% mothers reported overall positive mother-child experience while the rest describe overall negative feelings. The unpleasant mothers perform relatively higher scores in comparison to their pleasant counterparts in Symptom Checklist 90 test and meanwhile their children also got higher disorder rate in "children's externalizing behaviors, internalization and behavior disorder". Statistics also showed that children's emotional disorder rate in externalizing is inversely proportional to mothers' educational levels. The difference in family structure appeared irrelevant to children's emotional status. The final noteworthy point was that children with mother whose monthly income was below 1 000 yuan had difference in response ability was significant. Conclusion Measurement of toddler's social emotional development and maternal emotion and psychological status is necessary, especially to children with emotional problems, for early professional intervention means more timely support.