Objective:To analyze the effect of nature cycle and hormone replacement treatment(HRT) cycle on the outcome of frozen-thawed embryo transfer(FET). Methods:In this retrospective study,727 FET cycles were divided into 2 groups:nature cycle(n=149) and HRT cycle(n=578). Pregnancy rate,spontaneous abortion rate,implantation rate and multiple pregnancy rate were compared between two groups. Results:FET cycle outcomes were similar between nature cycle and HRT cycle on pregnancy rates (39.6% vs 41.2%,P > 0.05),spontaneous abortion rates(5.4% vs 5.0%,P > 0.05),implantation rates(28.3% vs 27.6%,P > 0.05). There were significant differences of pregnancy rates between cleavage FET cycle and blastocyst FET cycle(66.7% vs 39.95,P < 0.05). There were no significant differences of monocyesis pregnancy rates and multiple pregnancy rates between nature cycle and HRT cycle(P > 0.05).Transfer with 3 embryos resulted in higher pregnancy rate and multiple pregnancy rate than transfer with 2 embryos (P < 0.05). Conclusions:FET cycle outcomes were similar between nature cycle and HRT cycle on pregnancy rate and spontaneous abortion rate. It should be more economical and easier for ovulatory patients to use nature cycle FET. Increasing number of FET embryo was associated with improved pregnancy rate and higher multiple pregnancy rate.