Abstract: A long lifetime and high effiency power supply for uninterrupted output based on supercapacitor is proposed in this paper. The operating life has been improved by using supercapcitor as maintaining power and capacitance can be optimized by boost topology. The operate time of the power supply is about 10s under the condition 5V@5A. The output voltage can be turned off rapidly and monotonically decreasing when the capacitor undervoltage. It can service most of requirements. Keyword: boost,supercapacitor,uninterrupted output,back power supply