In this study, we propose a technique of comprising personal digital assistants and wireless radio frequency identification(RFID) system to implement an intelligent police-use vehicle inquiry device. With the technology of scanned a tag sticked in the concerned vehicle by the RFID, all the information about this vehicle will be quickly checked with SQL data base and then be immediately displayed on the PDA. The proposed technology is not only a new developed technique, it can but also provide police to inquire vehicles with violate traffic regulation rule.