Objection To develop a animal model of human monozygotic twins. Methods C 57 BL/6J strain female mice mated with KM male mice, after seeing plug 3.5 days the compacted morulae and blastocysts were collected and bisected microsurgically by using special knife, obtained half embryos were cultured and observed. Results Take rate of bisection for morurae is 91.3%, developing rate is 57.1%, Whereas the take rate of bisection is 89.2%, the developing rate is 71.2% for blastocysts. Conclusion The F 1 demi-embryos from C 57 BL/6J and KM mice can develop in vitro after embryo bisection, the data may be useful in studying development and differentiation of monozygotic twins embryos as well as in establishing a animal model of human twins.