A CMOS current comparator circuit based on Wilson current source is proposed to solve the problems of high-power consumption and low precision of traditional current comparator. It consists of Wilson current source， differential amplifier and output gain stage. Because Wilson current source has better constant current characteristics and higher output impedance， the current comparator has higher comparative accuracy and low delay propagation characteristics. The HSPICE model parameters of TSMC 0.18 CMOS process are used to simulate the performance of the current comparator. The circuit has a high precision of 5 nA. When the input differential current is 1 μA， the delay is 2.2 ns， and the power consumption of the circuit is 95 μW at TT (typical) process angle. The results show that the CMOS current comparator has a high speed/power ratio， and its performance is less affected by the process deviation which is suitable for high-speed and low-power current-mode integrated circuits.