The invention relates to a method for regulating a metal gate work function for a PMOS (P-channel Metal Oxide Semiconductor) device. The method comprises the following steps of: depositing a metal nitride film or a metal film on a high-K medium by using a physical vapor-phase deposition method as a metal gate electrode; implanting elements of Al, Pt, Ru, Ga or Ir, and the like into the metal gateelectrode by adopting an ion implanting method; and driving doped metal ions onto the interfaces of the metal gate electrode and the high-K medium to form accumulation or react through the interfacesto generate a dipole so as to achieve the purpose of regulating the effective work function of a metal gate. The method has the advantages of universality, simple and convenient process, strong capacity of regulating the metal gate function and good compatibility with a CMOS (Complementary Metal-Oxide-Semiconductor Transistor) process.