Abstract: License plate location（LPL） is one of the most important roles in the license plate recognition（LPR） system.The paper projects the conception of non-orthogonal haar wavelet transform based on haar wavelet that improves the uncontinuity of haar wavelet transformation.Based on non-orthogonal haar wavelet transformation，this paper integrates the method called scanning line which is rapid and the mathematical morphology which can accurately find license plate，and gets one rapid algorithm of license plate location.Then the algorithm is realized and tested with visual c++6.0.Experimental results indicate that the ratio of right location of license plate is higher than 95% with this algorithm.It is robust，especially used for detecting oblique license plate.