Objective: This study aims to provide an evidence-based assessment of the benefits and harms of four transplantation methods so as to improve the superior pregnancy outcome and reduce the pregnancy rate of multiple embryos in the Mongoloid race. Design: Retrospective analysis Setting: Double Reproductive Centers of Medical University Population or Sample: 24,422 frozen-thawed embryo transfer (FET) cycles recorded from January 2015 to May 2018. Methods：A retrospective cohort study Main Outcome Measures: Biochemical pregnancy, clinical pregnancy, monozygotic twins, miscarriage, maternal complications, live birth. Results: Of the four groups, the biochemical pregnancy rate, the clinical pregnancy rate, and the live birth rate were the lowest in the C-1 group while they were the highest in the B-2 group. However, the B-2 group was accompanied with higher risks of miscarriage, maternal complications, twin births, preterm births and low birth weights. The biochemical pregnancy rates, the clinical pregnancy rates and the live birth rates in the C-2 group and B-1 group were statistically different, with different risks for monozygotic twins, miscarriages. Conclusion: Single blastocyst transplantation seems to be the best choice for all maternal ages to greatly reduce adverse neonatal outcomes. Tweetable abstract: This was a retrospective cohort study using the ART databases from two affiliated hospitals of Peking University. 24,422 frozen-thawed embryo transfer (FET) cycles recorded from January 2015 to May 2018 were selected to generate the research database which also included maternal characteristics.