Deterring the location of the plate is the first step in the car license plate detection. The output of this step should be accurate enough and also, its calculations will be completed within a short time. The reason for this is that the output of this stage is as input in the next steps. If the location determination phase encounters an error, the function of the next steps will also be interrupted. In this paper, a new method is presented using the improved contrast of the image, the removal of non-numerical characters, analysis and clustering of plaque characters in order to determine the location of an Iranian car license plate with dark characters on a bright background. The proposed method reduces the overall complexity of the algorithm and In addition to ease of implementation; the speed and efficiency of the system determine the location of the plaque. The proposed algorithm is independent of the number of vehicle plates in the image, the size of the image, the inclination, and the full scintillation of the plaque and In contrast to brightness variations, it is largely resistant(robust). The test results on two different data sets with 67 and 492 images respectively, with an accuracy of 100 and 99.59% with an error rate of 1.5 and 1.63, and an average of 109 and 17.5 milliseconds, respectively.