Abstract: Obj ective To observe the position fertilization (IVF)treatment cycle of in vitro cultivation quality blastocyst formation and analyze its relationship with pieces of D2D3 embryo cleav-age count and rating.Methods Cleavage stage 3 day (D3 )frozen surplus embryos were selected and cultured to blastocyst stage.Quality of blastocyst formation was observed,and at the same time their D2D3 embryo cleavage count and debris were discussed.Results The high quality D3 10 or more cells blastocyst formation rate was 38.9%,which was almost equal to 43.1%of 7 to 9 cells blastocyst formation rate (P>0 .05 ).7 to 9 cell quality blastocyst formation rate was 43 .1%, which was significantly higher than 10.2%of 4 to 6 cells (P<0.05).D2 4 cell quality blastocyst formation rate was 43.1%,which was significantly higher than 28.9%of 5 cells and 12.3%of 2 to 3 cells (P<0 .05 ).5 cells quality blastocyst formation rate was 28 .9%,which was almost equal to 23 .4%of 6 cells blastocyst formation rate (P>0 .05 ).Ⅰand classⅡD3 embryos pieces of high quality blastocyst formation rate was 36.4%,which was significantly higher than 6.1%of gradeⅢorⅣ(P<0 .05 ).Ⅰand class ⅡD2 embryos pieces of high quality blastocyst formation rate was 35.3%,which was significantly higher than 4.7% of grade Ⅲ or Ⅳ (P<0.05).Conclusion Extending IVF can effectively filter the embryo developmental potential.The more D3 embryo cleavage count ,the more high-quality blastocysts .D2 4 cells ,embryo blastocyst development ability is good.Ⅰand classⅡD2 and D3 embryos pieces of high quality blastocyst formation rate is higher.High quality blastocyst formation and D2 and D3 embryo cleavage count and debris are closely related to the ratings.