Objective: To investigate the distribution of various types of screen time and examine the association of screen time with psychological and behavioral development problems in children aged 3-6 years, so as to provide scientific basis for children s screen use and mental health promotion. Methods: A total of 3 875 mother child dyads who completed the follow up in Shanghai Maternal-Child Pairs Cohort were included. The daily usage time of children s tablet, mobile phone, TV, projectors, and other types of screens were obtained in questionnaire survey. Children s psychological and behavioral development problems were evaluated by Age-Stage Questionnaire, Third Edition (ASQ-3) and Strengths and Difficulties Questionnaire (Parent version) (SDQ). The Chi-square test, Mann Whitney U and Kruskal Wallis rank sum test were used to compare the detection rate of psychological and behavioral development problems and screen time in children with different characteristics. Multivariate binary Logistic regression was used to analyze the association of screen time with psychological and behavioral development problems. Results: There were 49.91% of children having screen time more than 1 h/d. Children s TV, tablet and mobile phone screen time were 0.39(0.25, 0.96 ), 0.25(0,0.61) and 0.18(0,0.25) h/d. The detection rates of suspected developmental delay in fine motor, problem solving and personal-social domains and pro social behavior deficiency and externalizing behaviors in boys (8.54%, 6.77%, 5.46%, 30.07 %, 27.39%) were higher than that in girls (4.64%, 4.85%, 2.48%, 22.10%, 22.36%) ( χ 2=23.76, 6.49, 22.37, 31.81, 13.06, P <0.05). There were statistically significant differences in the detection rates of suspected developmental delay in communication, fine motor and problem solving, as well as internalizing behavior and externalizing behavior of children with different parents educational levels ( χ 2=14.37, 15.18, 21.10, 11.66, 9.27; 16.34, 26.75, 32.89, 16.97, 6.37, P <0.05). There were significant differences in the detection rates of suspected developmental delay in problem solving, prosocial behavior deficiency, internalizing behavior and externalizing behavior of children whose mothers had anxiety/depression symptoms during pregnancy ( χ 2= 5.61 , 9.05, 21.90, 7.17; 8.75, 6.06, 12.76 , 5.55, P <0.05). The average total screen time of boys was longer than that of girls (1.07, 1.00 h/d, Z=-2.08, P =0.04). Compared with children with other educational levels of their parents, the total screen time, mobile phone and TV screen time of children whose parents had college education or above were short (father: H =42.01, 44.49 , 21.24, mother: H =42.31, 39.21 , 26.47, P <0.01). Among all types of screen time, mobile phone screen time had the most impact on psychological and behavioral development. More mobile phone screen time increased the risk of suspected developmental delay and abnormal emotional behavior ( P < 0.05). Screen time of tablet, mobile phone and TV were positively correlated with externalizing behavior ( OR=1.36, 1.57, 1.27 , P <0.05). Conclusions Screen time is related to children s psychological and behavioral development problems and mobile phones affect the most. Parents should limit their children s screen time to avoid excessive screen time affecting their psychological and behavioral development.