Compared with short wave and medium wave devices, long wave infrared detectors have larger photocurrent and dark current, so they need strong charge storage capacity. However, the use of traditional analog pixel readout circuit technology is severely limited by charge storage ability, which makes it difficult to improve the dynamic range and signal-to-noise ratio of long-wave detector, restricting the development and application of long-wave infrared imaging system. In this paper, a pixel-level digital readout circuit technology is proposed, which overcomes the limitation of charge storage capacity of traditional analog integration scheme.The digital signal output of detector is realized. The dynamic range, anti-interference ability and frame rate of detector improve greatly. This technique is an effective way to improve the performance of long wave detector.Based on this technology, a digital readout circuit with 320X256 array and pixel spacing of 30 um is designed The output is transmitted by LVDS. The simulation results show that the maximum frame rate of the circuit can reach 1000 Hz, and the dynamic range is greater than 95 dR