Method and system for detecting whether modules of vehicle are replaced or not

The invention relates to a method for detecting whether modules of a vehicle are replaced or not. The method comprises the following steps that a main control unit of the vehicle automatically generates a random code during factory matching and transmits the random code to detected modules and the random code is stored in each detected module; when the vehicle is begun to be used, a detection function is activated; the main control unit periodically sends the random code to the detected modules, and the detected modules judge whether the random code stored in respective detected modules is consistent with the random code currently received from the main control unit or not. According to the method for detecting whether the modules of a vehicle are replaced or not, whether the modules in the vehicle are replaced or not and whether potential theft exists or not can be detected.