A strained germanium field effect transistor (FET) and method of making the same, comprise forming a germanium layer on a substrate, then forming a Si protective layer on the germanium layer, next forming a gate insulation layer on the Si protective layer, and fmally positioning a gate on the gate insulation layer. The germanium layer is used as a carrier transport channel of the strained germanium FET to improve the drive current and the carrier mobility, and to increase the devices performance effectively. And because the Si protective layer is on the germanium layer, the interface property between the germanium layer and the gate insulation layer is improved.