【Objective】 To explore the applicability of Bayley Scales of Infant and Toddler Development-Third Edition(Bayley-Ⅲ) to assess the development of infants and toddlers in Shanghai and to analyze the reliability and validity. 【Methods】 457 normal infants and toddlers aged 0~42 months were tested with Bayley-Ⅲ. Among those children, 33 were scored by two examiners during test, 24 were retested after a week and 34 were tested with both Bayley-Ⅲ and Gesell on the same day. 【Results】 1)The test-retest reliability was 0.711~0.831 (P<0.001). Cronbach's α coefficient was 0.956~0.993. The inter-rater reliability was 0.906~0.950(P<0.001). 2)There was low correlation between three kinds of composite score in Bayley-Ⅲ and applicability developmental quotient (DQ) in Gesell(r=0.119~0.367). 3) The mean score of 457 normal infants and toddlers was higher than the norm reference score of American in cognitive, language and motor subscales (P<0.001), but lower in adaptive behavior scale (P<0.001). 4) Girls scored higher than boys in cognitive, language and social-emotional subscales. 【Conclusions】 There are some differences in development between Chinese and American children, but Bayley-Ⅲ shows good reliability. It is feasible to assess the development of infants and toddlers in china.