It is based on corecontrolling chip of STM32F103C8T6 MCU to design a DC voltage charger with USB interface. The system uses the integrated high speed A/D inside STM32F103C8T6 to collect the charge voltage and current with high efficiency of TPS5430 as the power supply, low power consumption, high accuracy of the INA128P as the amplifying circuit. The test results prove that the charger can achieve 5 V, 2 A maximum charging current output and realtime display on LCD 12864 in a dynamic way. The charger is also equipped with the overload and overvoltage undervoltage protection. So the charger has high practical value.