A high-sensitivity long wavelength infrared detection system was developed based on the type-II superlattice 320 × 256 long wavelength infrared detector. The technical specifications of the type-II superlattice infrared detector and the main structure and working mode of the infrared system are introduced. In order to give full play to the sensitivity of the infrared detector, a high-sensitivity information acquisition system was developed. The software and hardware design of the information acquisition system is introduced. The information acquisition system adopted an adaptive signal conditioning technology to reduce information acquisition noise and improve sensitivity and dynamic range of the infrared system. Finally, the information acquisition noise test, system performance test and outfield imaging experiment are carried out for the whole long wavelength infrared detection system. The experimental results show that the information acquisition noise of the long wave infrared detection system is 0.065 mV, the NETD is19.6 mK, and the blackbody detectivity is 7.72×1010. The quality of outfield imaging is good, the details of the images are clear and the contrast is high. The long wavelength infrared detection system is conducive to the application of type-II superlattice infrared detectors in high sensitivity long wavelength infrared remote sensing.