A radio diagnosis device for car faults includes: a host including a CPU, a supply module, a radio communication module, an input module, a display module, a test card and a printer, the diagnosis test box including a general interface circuit, a primary CPU, a slave CPU, a program storage, a data storage amd a radio communication module, in which, the host is separated with the box, which is connected with a special diagnosis base in communication, the host and the box communicate by the radio communication module to realize data exchange and transmission and the host touch screen inputs instructions to realize test to different kinds of cars and the color LCD displays the result.