Abstract: Objective To study the value of open pulled straw(OPS) method on cryopreservation of embryos between HBV transgenic mice and cataract mice (CM). Methods Ethylene glygol (EG) is used as the cryoprotectant, OPS method is adopted to carry out vitrification freezing for 3.5d embryo of CM，P₂₁^HBxPHBx and KM mice, and compared the numbers of embryo，recovery rate and developmental rate after defrosting of KM, CM and P₂₁^HBxPHBx.Results The average embryo numbers of KM , CM，and P₂₁^HBxPHBx 31.12,19.32，9.14 respectively . The recovery rates are 88.7%, 81.1% and 80.3% respectively.The developmental rates are 82.6%，79.4% and 56.6% respectively. The embryo numbers ofP₂₁^HBxPHBx are lower than those of KM . The recovery rates are not significantly different in three kinds of mice .The embryo developmental rate after defrosting of P₂₁^HBxPHBx is lower than that of KM. Conclusion The superovulated numbers and developmental rate after defrosting 0f P₂₁^HBxPHBx are iower than those of KM，and there is no significant difference between CM and KM.

Key words: Ciyopreservation, Open pulled straw, HBV Transgenic, Cataract mice