A high-performance low-noise current readout circuit working at 77 K for IR detectors is designed by using a folded-cascode structure.Its noise characteristics were analyzed and the methods for decreasing noise were put forward.This circuit was fabricated in 1.2 μm CMOS technology.The test result shows that the circuit can work at the temperature of 77 K,its feedback resistance was 41×106Ω,the equivalent input noise current is 0.03 pA/Hz1/2.