Background There is a lack of research evidence on the association between sugar-sweetened beverage (SSB) consumption and gestational diabetes mellitus (GDM) in China. Objective To explore the association between frequency of SSB consumption before pregnancy and risk of GDM in pregnant women in Shaanxi Province, and to provide a scientific basis for targeted interventions to control maternal blood glucose. Methods The recruitment to the China Birth Cohort study started in October 2020. Pregnant women at 6-16 weeks who had their first prenatal examination at five hospitals in Shaanxi Province were recruited. A maternal health questionnaire was used to collect basic information about pregnant women. A semi-quantitative food frequency questionnaire was used to collect the consumption of carbonated beverages, fruit and vegetable juice beverages, coffee beverages, and milk tea beverages in one year before pregnancy, which were summed to obtain the SSB consumption. Pregnant women were divided into three groups according to SSB consumption, namely <1 serving·week⁻¹, 1-4 servings·week⁻¹, and ≥5 servings·week⁻¹. GDM was confirmed by oral glucose tolerance test (OGTT) between 24-28 weeks of gestation. A binary logistic regression model was applied to explore the association between SSB consumption and risk of GDM. Multiple linear regression was applied to investigate the associations between SSB consumption (per 1-serving·d⁻¹ increase) and OGTT fasting plasma glucose, 1-hour glucose, and 2-hour glucose. Results A total of 3811 pregnant women were finally enrolled in this study, of which 752 developed GDM, with an incidence rate of 19.7%. The incidence rates of GDM in pregnant women with SSB consumption frequency of <1 serving·week⁻¹, 1-4 servings·week⁻¹, and ≥5 servings·week⁻¹ were 18.0%, 21.1%, and 26.8%, respectively. After adjusting for maternal age, pre-pregnancy body mass index (BMI), education, number of children born, family history of diabetes, smoking, alcohol consumption, physical activity level, and total energy intake, the risk of GDM increased by 26% (OR=1.26, 95%CI: 1.05, 1.50) in the 1-4 servings·week⁻¹ group and by 76% (OR=1.76, 95%CI: 1.31, 2.38) in the ≥5 servings·week⁻¹ group compared to the <1 serving·week⁻¹ SSB consumption group, respectively. Further stratified analysis revealed no interaction effect (P_interaction>0.05) between SSB consumption and maternal age, pre-pregnancy BMI, or first labor or not. For each additional SSB consumption per day, the risk of GDM increased by 94% (OR=1.94, 95%CI: 1.37, 2.75); and the maternal OGTT 1-hour glucose and 2-hour glucose increased by 0.33 mmol·L⁻¹ and 0.18 mmol·L⁻¹, respectively (P<0.05), and no significant increase in fasting plasma glucose was found (P>0.05). Conclusion Higher SSB consumption before pregnancy increases the risk of GDM in pregnant women.