Objective To compare the relative expression of the Mgst1 gene and the expression distribution of Mgst1 protein in mouse hatching blastocysts and dormant embryos before and after cryopreservation. The role of the Mgst1 gene during the programmed freezing of mouse embryos was analyzed to provide a new theoretical basis for the study of embryo-related antifreeze mechanisms. Methods Immunofluorescence images of the expression distribution of Mgst1 protein in embryos were detected by confocal microscopy. By qRT-PCR, the relative gene expression of Mgst1 was determined. Results Mgst1 protein was expressed in mouse normal hatched blastocysts and dormant embryos before and after cryopreservation. There was no significant difference in the relative expressions of Mgst1 gene between hatched blastocysts and dormant embryos before cryopreservation (P > 0. 05). Compared with the normal hatched blastocysts before and after cryopreservation, the relative gene expression of Mgst1 in normal hatched blastocysts was significantly upregulated after cryopreservation ( P < 0. 05), and its relative expression in dormant embryos was markedly upregulated after cryopreservation ( P < 0. 01). Compared with the normal hatched blastocysts after cryopreservation, the relative gene expression of Mgst1 in dormant embryos was significantly upregulated (P < 0. 05). Conclusions The Mgst1 gene may play an important role in the antifreeze mechanism of mouse embryos.