This paper mainly studies the input stage design of the readout circuit of the infrared detector.For the short wave infrared signal,the capacitive feedback transconductance amplifier(CTIA) readout circuit has the characteristics of high injection efficiency.In this paper,an input stage structure of CTIA readout circuit with background dark current suppression is designed.This structure can achieve a long integration time of more than 300 μs,and in 77 K low temperature environment,the detector receives short wave small signal and the injection current is 0~800 pA. Compared with the input stage of traditional CTIA readout circuit,it can effectively suppress the background dark current and provide a detector bias voltage stability improvement of 93.2 %.At the same time,the integration linearity is 99.97 %,which has good integration uniformity,sensitivity and dynamic range.