Objective To explore and analyze the application value of hormone replacement therapy in pregnancy with hypothyroidism or subclinical hypothyroidism. Methods A total of 117 pregnant women with hypothyroidism and subclinical hypothyroidism in Nanshan Shekou People′s Hospital of Shenzhen from January 2018 to November 2019 were selected and divided into control group (53 cases) and observation group (64 cases) according to the order of hospitalization. The control group was treated with conventional treatment, and the observation group was treated with hormone replacement therapy. Thyroid function, incidence of complications, postpartum hemorrhage and pregnancy outcome were compared between the two groups before and after treatment. Results After 6 weeks of treatment, the thyroid stimulating hormone, serum free thyroxine and serum free triiodothyronine in the observation group were lower than those in the control group, the differences were statistically significant (P<0.05). The total incidence of complications in the observation group was not statistically significant compared with that in the control group (P>0.05). The bleeding of 2 h postpartum and 24 h postpartum in the observation group was less than that in the control group, the differences were statistically significant (P<0.05). The gestational week of delivery in the observation group was longer than that in the control group, and the milk opening rate, neonatal weight, Apgar score and pH value of umbilical artery blood gas in the observation group were higher than those in the control group, the differences were statistically significant (P<0.05).Conclusion The drug treatment for pregnant women with hypothyroidism or subclinical hypothyroidism should be based on conventional treatment, and then combined with hormone replacement therapy; it has significant advantages in improving blood lipid level, improving thyroid function and improving pregnancy outcome.