Abstract: Current sensing circuit is one of the most important component parts of current-control DC/DC convertor, its accuracy and response speed acquires more and more attention.We proposed a novel current sensing circuit in this paper, which does not use the operational amplifier, simplify the circuit structure, reducing power consumption, at the same time, the introduction of the compensation current further improves the sensing accuracy.Designed the circuit based on 0.5 μm CMOS process, HSPICE simulation results show that the circuit has a high sensing accuracy up to 99.9%, and as workload, input voltage and temperature changes, the fluctuation of sensing accuracy of the circuit is very small.