Abstract: 【Abstract】 Objective To investigate the associations between paternal factors and low birth weight (LBW). Methods A case-control study included 332 LBW infants and 4 979 normal birthweight infants who were delivered at Gansu Provincial Maternity and Child-care Hospital between February 2017 and December 2018. Pregnant women were surveyed using the Pregnant Health Questionnaire developed by Yale University. General data of the parents were collected and body mass index (BMI) was calculated. Health status of pregnant women during pregnancy, information on delivery and neonatal conditions were collected.The chi square test was used for comparison of counting data rates. Univariate and multivariate logistic regression were used to analyze the correlation strength OR (univariate analysis) and adjusted OR (aOR) between various factors and LBW infants. Results ① There were no significant differences between the low birth weight group and the normal birth weight group in maternal ethnicity, pre-pregnancy weight, prepregnancy BMI, and maternal smoking history during pregnancy (P>0.05). ② Univariate analysis showed that fathers ≤20 years old, 21-25 years old, ≥40 years old were more likely to have LBW in their children. The paternal height >175 cm, body weight >75 kg, and BMI 24-27.9 kg/m2 were protective factors for LBW. The father height ≤165cm, weight ≤60 kg, BMI<18.5 kg/m2 and smoking before pregnancy, early pregnancy and second trimester, third trimester were the risk factors of LBW. ③ Multivariate logistic regression analysis showed that the father's age ≤20 years old (aOR =7.183, 95%CI: 1.842-28.002), the father's education level was high school or below (P <0.05), the father's height ≤165 cm (aOR =1.843, 95%CI: 1.107-3.069) and father's BMI<18.5 kg/m2 (aOR =2.494, 95%CI: 1.299-4.788) were independent risk factors for the occurrence of LBW. Fatherly smoking in the presence of pregnant women before, in the first, second, and third trimesters was not found to be an independent risk factor for low birth weight in the study population. Conclusion In pregnancy health care, we should not only pay attention to the mother, but also strengthen the father's health education. Raising the childbearing age couple's self-health awareness and father's good life behavior can effectively reduce the occurrence of low birth weight.