A novel Automatic Target Recognition(ATR) algorithm based on imaging Laser Radar(Ladar) is proposed to solve the target recognition difficulty caused by a tree sheltering,and the algorithms such as data classification,data mosaic,target pose adjustment and target recognition based on a height histogram are studied.The scene data are classified into several parts (ground,targets and trees) by using an image processing technique,and the translation matrixes among different views are calculated from coarse to fine according to their inherent attributions.Then,the data from different views are integrated together.According to its normal directions,each target pose is adjusted to the top view,and its height histogram can be calculated.Finally,the target is recognized by matching the target height histogram with the saved model height histograms.Experimental results indicate that the extracted target part is more than 90% of the whole target area and the recognition ratio is more than 99%,which satisfies the ATR requirements in stabilization,higher recognition ratios and strong anti-jamming.