With the development of remote sensing technology, the detection sensitivity of infrared system is increasingly required. The infrared imaging detection technology based on linear avalanche device can effectively improve the detection sensitivity in high frame frequency applications. Based on the short-wave infrared linear avalanche detector assembly of 512X512, a small-aperture and lightweight infrared imaging system is designed and its performance is tested under low reverse bias. The test results show that the increase of SNR of the imaging system based on the linear avalanche infrared detector is basically linear with the multiplication factor M under short integration time, and the SNR of the system is 3 times that of the traditional camera of the same caliber.