There has been a lot of interest in the Si based strained technology lately, especially the modification of band structures which provides a theoretical basis for the design of the high-speed and high-performance devices and circuits. The band structure models of strained Si1-xGex on （001）,（101）,（111） relaxed Si are set up using K.P perturbation method coupled with deformation potential theory. Ge fraction （x） dependence of the conduction band　（CB） and the valence band　（VB） edge levels, CB and VB splitting energy and the indirect bandgap were obtained. The quantitative data from the models can supply valuable references to the design of devices.