Objective: To investigate the current prevalence of excessive weight gain during pregnancy among pregnant and lying-in women in Xining City and to identify the influencing factors, so as to provide insights into reasonable weight control during pregnancy. Methods: The pregnant and lying-in women who were registered and delivered in the Red Cross Hospital of Qinghai Province, the Affiliated Hospital of Qinghai University and the First People's Hospital of Xining City from August 2021 to July 2022 were enrolled. Women's demographics, health status during pregnancy, diet, sleep and exercise were collected through prenatal testing data and questionnaires. Excessive weight gain during pregnancy was identified according to "Weight monitoring and evaluation during pregnancy of Chinese Women" (T/CNSS 009-2021), and the factors affecting excessive weight gain during pregnancy were identified using a multivariable logistic regression model. Results: A total of 902 questionnaires were allocated and 882 valid questionnaires were recovered, with an effective recovery rate of 97.78%. The pregnant and lying-in women had a mean age of (29.06±4.16) years, mean pregestational body mass index of (20.44±2.20) kg/m2 and mean gestational weight gain of (14.17±3.11) kg, and there were 447 primiparas (50.68%) and 360 women with excessive weight gain during pregnancy (40.82%). Multivariable logistic regression analysis identified an educational level of senior high school/technical secondary school (OR=1.400, 95%CI: 1.037-1.889), annual household income of >200 000 Yuan (OR=2.385, 95%CI: 1.924-2.956), a family history of diabetes (OR=1.475, 95%CI: 1.180-1.844), pregestational overweight/obesity (OR=4.079, 95%CI: 2.471-6.734), gestational hypertension (OR=2.061, 95%CI: 1.027-4.136), anxiety (OR=1.315, 95%CI: 1.139-1.518) and preference for sour foods (OR=1.715, 95%CI: 1.237-2.376) as risk factors for excessive weight gain during pregnancy, and early pregnancy reaction as a protective factor (OR=0.636, 95%CI: 0.546-0.742). Conclusions The prevalence of excessive weight gain during pregnancy was high in Xining City, and educational level, annual household income, family history of diabetes, pregestational body mass index, pregnant complications and dietary habits are factors affecting excessive weight gain during pregnancy.