Explore the variation of hsMAD2 protein and gene expression level in the chromosome segregation of human embryo.Taking 50 spontaneously aborted embryos treated in our hospital as research objects, detect the embryo villi chromosomal numbers of the patients by FISH.Divide the patients into normal group and abnormal group based on the chromosome number.Detect the hsMAD2 protein and gene expression level in villi tissues of the two patient embryos groups by western blotting and qPCR respectively.Results showed that (1) the two patient groups are comparable because no statistical difference (P> 0.05) existed in their general conditions, such as gestational age, gravidity and gestational week.(2) 28 embryos with chromosome abnormalities are detected in embryos of 50 patients with spontaneous abortion, accounting for 56% (28/50).8 chimeras are detected in them, accounting for 16%.(3) The hsMAD2 protein level in villi of abnormal group embryos is (0.88±0.20), and its gene level is (23.46±0.07).Compared with the corresponding values (0.61±0.19) and (18.35±0.10) of normal group, the statistical difference is (P<0.05).Draw Conclusions that (1) the chromosome numerical abnormality is closely associated with the spontaneous abortion.(2) the hsMAD2 factor has a checkpoint effect on cell cycle.(3) Its retardation effect on the mitotic cell division process plays an important role in maintaining normal and steady chromosome segregation.