Abstract: Based on Eshelby's theory and considering the micro voids inside the tungsten alloy as the third phase, a constitutive frame involving damage factor was constructed by means of Eshelby's model of equivalent inclusions and Mori Tanaka uniform field method. Then, introducing the constitutive relationship of tungsten grain and matrix into the above frame, as a result, the constitutive equation involving damage factor of tungsten alloy is obtained. By use of a one dimensional finite differential Lagrange program, the numerical computing of the spalling phenomena of tungsten alloy was made and the agreement of the computing results with the experimental data is pretty well.