In this paper, threshold voltage model of quantum-well channel pMOSFET with p+polycrystalline SiGe gate and its cut-in voltage model were established based on solving Poisson equation while considering the impact of free carrier. The effects of relevant parameters (Ge concentration of poly SiGe gate, Ge concentration of quantum-well SiGe channel, thickness of oxide layer, thickness of Si cap layer, doping content of quantum-well SiGe channel, and doping content of substrate) on threshold voltage and cut-in voltage of the parasitic channel was analysed by numerical analysis, and obtained the methods to restrain the opening of parasitic channel. The results of the models are in good agreement wih that of experiment reported as well as of ISE simulation.