Using diamond-anvel cell high pressure equipment, the phase transition of Cd1-xMnxSe under high pressure has been measured by optical absorption and X-ray diffraction methods, It has been found that the phase transition is irreversible. Under common pressure, Cd1-xMnxSe has wurzite structure, but it transforms to Nad structure under high pressure. When the pressure is removed, Cd1-xMnxSe becomes zinc blend structure. In addition, the relation between the pressure of phase transition and component x is also obtained.