Abstract: Range alignment is a crucial problem in high range resolution profile(HRRP) based on radar automatic recognition.Comparing with correlation based range alignment,absolute alignment has the advantage of low computation complexity.Although its alignment accuracy is decreased,recognition ratio are not decreased,what's more,computation complexity is observably lowered because minimum Euclidean distance rule which is the simplest classification is applied to classify,.This paper will introduce three kinds of classification based different absolute alignment method-Zero Phase Representation(ZPR),Zero Linear Phase Representation(ZLPR),Barycenter Representation.Then we take theoretic analysis and the comparison of their performance.The experimental results show the three methods can all achieve a good recognition performance with low computation complexity.