【Objective】To explore the application prospect of single embryo transfer（SET）in assisted reproduction.【Methods】A total of 5 130 cases of fresh and frozen embryo transfer in the Reproductive Center of the First Affiliated Hospital，Sun Yat- sen University in the recent two years were analyzed retrospectively. To analyze the main outcome of clinical pregnancy in different age groups，we classified the SET cycles into 4 groups of fresh or frozen，elective or obliged.【Results】In non-preimplantation genetic testing（PGT）elective SET cycles，the clinical pregnancy rate of the day 3 embryos（D3）and day 6 embryos（D6）in patients under 35 were as high as 35%. The clinical pregnancy rate of day 5 embryos（D5）was 50% approximately. While in PGT cycles，the clinical pregnancy rate of patients less than 42 years old was 45% ，especially implantation rate of D5 embryos was close to 60% in all patients under 40. With the increase of age ，the pregnancy rate of SET decreased. In non-PGT group ，D3 embryos showed significant difference in either elective/obliged or fresh/frozen cycles（P < 0.001 for all）. In general，elective SET showed a higher pregnancy rate than obliged cycles. There was no significant difference between the elective and obliged frozen cycles of D5 or D6 embryos regarding clinical pregnancy rate（P = 0.074 and P = 0.596，respectively）. Elective D5 embryo transfer group had a higher pregnancy rate than that of the obliged group（P = 0.011）. However，there was no significant difference of clinical pregnancy rate between elective and obliged groups of D6 embryos（P = 0.979）. In non-PGT cycles ，clinical pregnancy rate was significantly different among different age groups of either elective/obliged or fresh/ frozen cycles（P < 0.001）. Obliged D3 and D6 embryo transfer groups showed the lowest pregnancy rate，and in PGT cycles of patients under 40，D5 embryo showed a higher pregnancy rate than that of D6 group as a whole（P < 0.001）.【Conclusion】The outcome of SET strategy seemed good in the last 2 years. In order to avoid perinatal complications caused by multiple fetuses ，clinicians and patients should actively promote and choose SET.