Objective: To compare the clinical results of the frozen-thawing blastoeyst transfer and the frozen-thawed embryo transfer following blastocyst culture, and explore available clinical applications of this two methods.Design: Retrospective cohort study.Materials and Methods: Retrospective cohort study for the FET patients from reproductive Medicine center of Third Affiliated Hospital of Guangzhou Medical University (January 2014 to December 2014), and the selection criteria of patients is under the age of 38, who giving the first transfer and the blastocyst transfer at the whole egg-picking cycle.After screening, incorporate 1029 cases in the statistics, which are divided into two group, that is Croup A: frozen-thawed embryo transfer after blastocyst culture;and Group B: the fresh embryo transfer after blastocyst culture, then re-freezing and blastocyst recovery.Main results : Group A's implantation rate is 46.8%, and Group B is 45.3%, there is no significant difference between the two groups(P>0.05);Group A's pregnahcy rate is 66.7%, and Group B is 64%(P>0.05).The multiple pregnancy rate of Group A is 49.3%, and G B is 50.7%, in which monozygotic twinning rate of Group A is 4.4% and Group B is 3.4%(P>0.05).The premature birth rate of Group A is 44.2% and Group B 33.3%, and the live birth rate of Group A is 57.3%and Group B 60.0%(P>0.05).Conclusions: There is no significant difference (P>0.05) in the implantation rate and pregnancy rate of two groups;the multiple pregnancy rate and monozygotic twinning rate of Group B are lower than that of Group A;but the premature birth rate of Group B is 33.3%, which is significantly lower than that of Group A-44.2%, and the live birth rate of Group B is significantly higher than that of Group A.In practice;when ≥4 fresh embryos are frozen, the blastocyst culture is carried out, and except for transplant (≤2 embryos are transplanted each cycle), the remaining embryos need to be re-frozen, so the double-freeze phenomenon appears.At present, the impact of double-freezing on the offspring remains controversial, therefore, it's recommended to implement blastocyst culture first and then freeze it when there are enough available embryos of patients.