The Led display in Kailong Plaza will be working for a long time everyday. And Led dispaly is the device that will consume large power. So the customer pay a lot of money for the grid power. LED is the component that drived by the current. Reducing the voltage can low down the power if the voltage is not changing . In the same time, using the lower resistance LED and drived to be lighting by a low voltage can make the whole system more high efficiency. Our company(Youyi Electronics) built-in the synchrounous rectification to reduce the waste of output. This design can save 15% energy. 545 days later, the money that saved may be equal with the price of power supply.