We have presented the Echo Broadening Effect of range-gated active imaging. It can respectively generate a head signal part and a tail signal part both sides of the echo signal profile. Our research demonstrates that the head signal and the tail signal impact the depth of view, detection range and imaging quality, especially the head signal. In order to solve the problems, we establish a model of the echo broadening effect, and analyze the signal energy characteristics and atmospheric backscatter. We have given the depth of view under the effect, verified it in experiment, and found that the reasonable choosing of the illuminator laser pulse time and the camera gate time can mange the effect to optimize range-gated imaging systems.© (2009) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.