There has been much interest in the Si-based strained technology lately. The research on the hole effective mass of Si-based strained material is the theoretical basis for the performance enhancement of Si-based strained PMOS devices. Based on the valence band E(k)-k relation of strained Si1-xGex/(111)Si, the hole effective mass along arbitrarily k wavevector direction were obtained. And the hole isotropic effective mass models were established. It was found that in comparison with relaxed Si, the more obvious anisotropy of the hole effective mass occurs in strained Si1-xGex/(111)Si and the hole isotropic effective mass of the top valence band decreases obviously with increasing Ge fraction. The results can supply valuable references to the conduction channel design related to stress and orientation in the Si-based strained PMOS devices.