Proposes a method which is based on C4.5 algorithm to recognize the parking plot. First, we should record the driving trajectory of the car by the sensors of smart phone in order to obtain the data, such as GPS data,velocity,accelerated velocity , etc. Then it is necessary that to have the data processed to improve the precision with several means , such as remove the flying spot , compensation algorithm , Kalman Filter and so on . The next step is to get the data further processed through C4.5 algorithm in order to acquire the state of the car . Finally , the algorithm of recognizing the parking plot is used to make sure whether the spot is a parking plot or not . The results of the processing shows that the method that mentioned above is effective to find the potential roadside parking plot .