Abstract: A high efficiency, low output ripple boost DC-DC converter was studied and designed. The DC-DC converter achieves high dc to dc converting efficiency,low power supply,low current and over current detection, saving mode control.The bias voltage of nodes inside of DC-DC converter are set by the bandgap reference voltage circuit,therefore, the system stability, suppressed power supply noise and effect of temperature variation is enhanced.The circuit simulation is based on the 0.25μm process,its conversion rate is grater than 90%.When input voltage is 2.5V,the output voltage are standard 3.3V and 5V.