Abstract： Objective： To observe the clinical effect of modified Dangui Zhifen Decoction in the treatment of gestational diabetes mellitus (GDM) and its effect on pregnancy outcome. Methods：A total of 62 GDM patients were selected and divided into the control group and the combination group according to the random number table method， with 31 cases in each group. The control group received routine treatment according to the GDM guidelines， and the combination group received modified Dangui Zhifen Decoction on the basis of the treatment of the control group. Both groups were treated for eight weeks. Evaluated the clinical effects of the two groups， and compared the blood glucose indicators， insulin resistance indicators， and pregnancy outcomes. Results： After treatment， the total effective rate was 96.77% in the combination group， which was higher than that of 74.19% in the control group (P＜0.05). After treatment， the fasting blood glucose (FBG)， 2-hour postprandial blood glucose (P2hBG)， and glycated hemoglobin (HbA1c) in the two groups were decreased when compared with those before treatment (P＜0.05)， and the combination group had lower levels of FBG， P2hBG， and HbA1c than the control group (P＜0.05). After treatment，the fasting insulin (FINS) and insulin resistance index (HOMA-IR) in the two groups were decreased when compared with those before treatment (P＜0.05)， and the FINS and HOMA-IR in the combination group were lower than those in the control group (P＜0.05). The cesarean section rate and incidence of fetal respiratory distress syndrome in the combination group were lower than those in the control group (P＜0.05). Conclusion： Modified Dangui Zhifen Decoction for GDM has a significant clinical effect， which can improve the blood glucose levels and insulin resistance of patients， and reduce adverse pregnancy outcomes.