It is a laborious process for people to search vehicles from a large amount of video volumes. We build a retrieval system of vehicles using a novel method which recognizes license plate from surveillance videos. The core idea is to automatically convert video information into text information such that the tracing problem of vehicles can be simplified since all records of vehicles are efficiently managed by a well-designed vehicle database. Using a vehicle license plate as a key word, the retrieval system not only finds completed information of the vehicle but also visualizes the track of the vehicle by an electrical map. Firstly we propose a new algorithm to detect the key frames including vehicle license plate characters from video. The most important part is to distinguish vehicles from other objects. Secondly, we correct vehicle plates using modified Radon Transform. Thirdly, some necessary information about vehicles like time stamps is also recorded in the vehicles database. The experimental results show that the proposed algorithm is effective to deal with videos and record vehicles information. Text and visualization information which the database provides can meet users' requirements for searching vehicles.