To investigate the correlation between the vitamin D for treating women after in vitro fertilization-embryo transfer (IVF-ET) and their pregnancy outcomes. Methods: From June 2021 to June 2022, 200 women who had undergone IVF-ET assisted pregnancy due to fallopian tube factors were selected. The serum 25-(OH) D level of these women was measured. According to the serum 25-(OH)D level, these women were divided 42 women with vitamin D level ≥30 ng/mL in group A and 158 women with vitamin D level <30 ng/mL in group B. The women in the group B were further divided into two groups according to the random number table method. And among them, 79 women with treatment of vitamin D drops-capsule type were in group B1, and 79 women without treatment of vitamin D drops-capsule type were in group B2. The clinical data, the situation of IVF-ET treatment, and the pregnancy outcomes of the women were compared among group B1, group B2, and group A. Spearman correlation analysis and binary Logistic regression analysis were used to identify the factors affecting the pregnancy outcomes of the women after IVF-ET. Results: There were significant differences in the serum 25-(OH) D level, the rates of oocytes retrieved, oocyte maturation, fertilization, and high-quality embryo of the women among group B2, group B1, and group A (P<0.05). The clinical pregnancy rate in group B2 (35.4%), in group B1 (51.9%), and in group A (71.4%) had increased gradually (P<0.05). There were significant differences in the age, the serum 25-(OH) D level, the endometrial thickness on the embryo transfer day, the sufficient serum 25-(OH) D or not, the number of oocytes retrieved, the oocyte maturation rate, the fertilization rate, and the high-quality embryo rate between the women with clinical pregnancy and the women without clinical pregnancy (P<0.05). Spearman correlation analysis showed that the serum 25-(OH) D level of the women was positively correlated with their clinical pregnancy situation (r=0.139, P=0.001). Logistic regression analysis showed that the age, the serum 25-(OH) D level, the endometrial thickness on the embryo transfer day, and the sufficient serum 25-(OH) D of the women were correlated with their clinical pregnancy (all P<0.05). Conclusion: The serum 25-(OH)D level of the women after IVF-ET is associated with their pregnancy outcomes. Vitamin D intervention for the women after IVF-ET has a positive effect on improving their pregnancy outcomes, and which can improve their clinical pregnancy rate.