Abstract: Objective:To analyze the incidence of early developmental lag in infants and its influencing factors.Methods:A total of 1, 859 infants and young children who underwent physical examination in the Department of Preventive Health Care, in the First Affiliated Hospital of Guangxi Medical University from June 2019 to July 2023 were selected as the screening objects and ages & stages questionnaires third version (ASQ-3) was used to evaluate them.The questionnaires were divided into five function areas (communication, gross movement, fine movement, problem-solving, individual-community); according to the function area scores, each function area was divided into three types of threshold values (above the threshold value, near the threshold value and below the threshold value); infants with the scores of one or more function areas below the threshold were characterized as developmental abnormalities.Results:A total of 560 among the 1, 859 infants gained the scores of one or more function areas below the threshold and the overall developmental abnormality rate was 30.12%.The problemsolving area occupied the highest proportion above the threshold value (77.41%); the fine movement area occupied the highest proportion near the threshold value(22.05%)and communication area occupied the highest proportion below the threshold value (14.90%).Mode of delivery, gestational week, birth weight and the education level of the primary caregivers were major factors influencing the development of infants and young children(P< 0.05).Caesarean section, preterm birth, low birth weight and low education level of the primary caregivers increased the risk of abnormal infant development.The predicted coincidence rate of the logistic regression model was 75.20%.Conclusion:The use of ASQ-3 can simply and effectively screen infants and young children who may be developmentally retarded.Prenatal care should be strengthened to avoid premature delivery, reduce cesarean section, reduce the birth of low weight infants, and strengthen early education for infants and young children to promote their comprehensive development level.