Objective: To explore the impact of maternal anxiety during pregnancy on social emotional development of toddlers aged 1-3 year old, so as to provide references for scientific early parenting and early intervention for toddlers with social emotional difficulties. Methods: From September 2022 to March 2023, a total of 815 toddlers aged 1-3 who underwent physical examinations and their mothers at Nantong Maternal and Child Health Hospital were enrolled. The Chinese Infant Toddler Social and Emotional Assessment (CITSEA) was used to evaluate the social emotional ability among toddlers. Maternal anxiety evaluated using the Self rating Anxiety Scale (SAS) during prenatal visit was collected. Results: The average scores on the externalizing, internalizing, dysregulation and competence domains of the CITSEA were (49.40±9.48,47.42±9.60,48.67± 10.15 , 50.07± 10.20), respectively. Among boys, the score of externalizing domain (50.89±9.45) was higher than that of girls (48.76± 9.50 ), while the score of competence domain (49.22±10.30) was lower than that of girls (51.17±9.84), and the differences were statistically significant( t =2.10, -3.03, P <0.05). The detection rates of abnormalities in the externalizing, internalizing, dysregulation, and competence domains were 7.36%, 7.12%, 7.61%, and 7.24%, respectively. Among them, boys (8.43%,6.32%, 7.96 %,7.49%) and girls (6.19%, 7.99 %,7.22%,6.96%) showed no statistical differences ( χ 2=1.50, 0.85, 0.16, 0.09, P >0.05). There were significant differences in externalizing domain scores（47.77±9.52，49.56±8.95，52.51±9.77） and competence domain scores（51.70±10.38，49.65±10.05，46.68±10.03） among toddlers of different maternal anxiety（normal, mild, moderate to severe） （ F =7.05,7.10, P <0.01）. There were significant differences in the abnormal detection rate of externalizing domain （4.81%，7.54%，11.17%） and competence domain（4.81%，6.96%，11.73%）（ χ 2=6.60，7.98， P ＜0.05）. Conclusion Maternal anxiety during pregnancy has a negative impact on the social emotional development among toddlers. In order to improve social emotional development of toddlers, multidimensional social support and education during pregnancy should be carried out.