Objective To explore the effect of a psychological intervention program based on dyadic coping theory on patients with gestational diabetes mellitus （GDM）. Methods Totally, 110 GDM women were recruited and divided into 2 groups of 55 cases each, according to the time spans when they were seeking medical help.The control group was given routine prenatal guidance, while the intervention group was subjected to a psychological intervention program developed based on dyadic coping theory.Patients′ self-management ability,fasting blood glucose （FBG） level, 2 h postprandial blood glucose （2 h PG） level, pregnancy-related anxiety and depression were measured before and 8 weeks into the intervention. Results After intervention, the intervention group showed lower level of FBG and 2 h PG, and lower scores of pregnancy-related anxiety and depression, while having higher self-management scores, than the controls (P＜0.01 for all). Conclusion The psychological intervention program developed based on dyadic coping theory help improve self-management ability, boost blood glucose control, and reduce the level of pregnancy-related anxiety and depression in GDM patients.