Objective To compare the clinical therapeutic efficacy of Dydrogesterone and Progesterone combined with HCG respectively in the treatment of Unexplained recurrent spontaneous abortion(URSA). Methods A total of 125 patients diagnosed URSA in Zhuhai Maternity and Child Health Hospital were randomly divided into two groups, with 63 cases (Dydrogesterone Group) treated by dydrogesterone combined with HCG and 62 cases (Progesterone Group) treated by Progesterone combined with HCG. The serum P, HCG and the pregnancy outcomes and adverse reactions of patients in two groups were compared respectively. Results Within 6-8 gestational weeks, the serum P in two groups showed no significant difference(P>0.05), but the serum HCG of the Dydrogesterone Group was higher than that of the Progesterone Group (P<0.05). During 10-12 gestational weeks, the serum P and HCG of Dydrogesterone Group were all significantly higher than Progesterone Group (P<0.05). The abortion rate, the term birth rate, and adverse reaction rate in two groups were obviously different (P<0.05). The abortion rate and adverse reaction rate of the Dydrogesterone Group were lower, but the term birth rate was higher. Conclusion In combination with HCG, the therapy on URSA by dydrogesterone has the better clinical effects than by progesterone, and has fewer adverse reactions as well,thus worth spreading.