To improve the capability of space-based surveillance for space targets， this paper researches the Moving Target Indicator (MTI) based on time-domain projecting image sequences for suppressing starry sky background.The MTI has been used in a spaceborn signal processor on the USA Midcourse Space Experiment for target detection and tracking. According to the in-depth study of MTI algorithm, a new method is proposed to suppress the background of cluttered cloud based on the standardized maximum projection of temporal difference. The mathematical principle and the operator design method of temporal projection are given. Then, considering the statistical characteristics of cluttered cloud, the two Improved MTIs(IMTIs),namely, the temporal difference operator on an adjacent frame and the estimated median operator, are introduced to the MTI to enhance the clutter suppression. Finally, the experimental method based on the cloud background data acquired is designed to analyze the algorithm performance of different projection methods as well as the main factors affecting on the algorithm. The experimental results show that the output Signal-to-clutter Ratio(SCR) of IMTI reaches more than 5.8 when the input SCR of a small target is less 2.0, which has been improved by 1 in average as compared with that of MTI.It concludes that the IMTI can effectively solve the dim target detection problem of cluttered cloud image background.