A new strained Si MOSFET structure with hetero-polycrystalline SiGe gate was studied, which combines the advantages of “gate engineering” and “strain engineering”. The new structure improved the carrier transport efficiency, suppressed the short-channel effects (SCE), and enhanced the performance on the basis of strain. Then a physically modeling strategy such as quasi-2D surface potential of strong inversion, threshold voltage, and channel current was presented for the strained Si NMOSFET. Finally, the above model was computed and the results were analyzed.