Based on two ways of light interference to LLL(Low-light-level) imaging system, the transmission model of light interference was established. Response characteristics of LLL imaging system was also analysed, and quantitative relation model of light radiant energy with response characteristics was also established. With simulation platform designed based on the data of theory and practice, low-light-level imaging under light interference was simulated. Computing results of gray mean, mean-square error and correlation function indicate that the quality of low-light-level imaging is directly related to the position and lightness of light interference source. The different position also can lead to different trend of correlation function. The light interference experiment was carried out, whose results were in agreement with simulation. It also indicate that the contrast between target and background is increased under light interference. And it is gradually decreased with increasing interference distance untill less then without interference.