In order to reduce the on-resistance of the trench MOS devices, a scheme of injecting N-type impurity into the body region of the conventional trench MOS devices was proposed, and the concentration distribution of impurity in the body region was optimized to reduce the on-resistance. The simulation results show that the specific on-resistance and threshold voltage can be reduced by 13% and 218% respectively when arsenic is injected into the N+ source area at an energy of 300 keV and a dose of 7×1012 cm-2. After the contact hole is etched, phosphorus is injected. Under the condition of energy of 100 keV and dose of 4×1012 cm-2, the specific on-resistance is reduced by 43% and the threshold voltage is almost unchanged.