Abstract: Objective To observe the therapeutic effect of dydrogesterone and human chorionic gonadotropin(HCG)in the treatment of threatened abortion and its effect on pregnancy associated protein A(APAPP-A), fetal fibronectin(fFN)and inhibin A. Methods A total of 180 threatened abortion women were selected and divided into control group and study group according to the random throwing method. The control group was treated with progesterone combined with HCG, and the study group was treated with dydrogesterone combined with HCG. The treatment effects, adverse reactions, PAPP-A, fFN, inhibin A levels, progesterone, and estradiol levels before and after treatment were compared between the two groups. Results The effective rate of treatment in the study group was 90.00%, which was higher than 76.67% in the control group, the difference was significant(P<0.05); the incidence of adverse reactions showed no significant differences between the two groups(P>0.05); after treatment, the levels of PAPP-A and inhibin A in the study group were higher, and the fFN level was significantly lower than that in the control group(P<0.05); the levels of progesterone and estradiol before treatment in the two groups showed no significant differences(P>0.05), but were significantly higher in the study group after treatment than those of the control group(P<0.05). Conclusion Dydrogesterone and HCG in combination have a significant therapeutic effect on threatened abortion, and can increase the levels of PAPP-A, inhibin A, progesterone and estradiol, and decrease the level of fFN.