A multi-mode control strategy is presented and implemented to reduce the standby power and increase the efficiency of the switch-mode power supply （SMPS）. Three different modes: quasi-resonant (QR) mode, pulse frequency modulation （PFM）mode and pulse skipping modulation （PSM）mode are applied in the strategy. In QR mode, the efficiency is high when the load is heavy, but the power loss of the switch is larger as the load is heavier. In PFM mode, the efficiency is high when the load is medium, and the switch frequency varies according to different loads to avoid excessive power loss. The efficiency in PSM mode is high when the load is light, and switch turns off for a set amount of time to further decrease the power loss. A chip was designed and fabricated on 700 V BCD technology and the optimization was achieved according to different loads. Compared to the conventional pulse width modulation （PWM）mode, the novel strategy can greatly reduce the no-load power consumption and increase the average efficiency in the full range of variable load. To verify the performance of the proposed strategy, a 12 W (12 V/ 1 A) laboratory prototype was built. The experimental results  show that the SMPS can work adaptively in different modes according to variable loads. The measured average efficiency is over 84% and the standby power consumption is less than 90 mW, which both fully meet the requirements of version 20 Energy Star specification．