A detecting device for coating leakage points in a petroleum pipe is disclosed and comprises a pipe rack, a detecting rack, four detecting gun tubes and a leakage point counter. A motor transmission mechanism and a pneumatic telescopic slide table are arranged on the detecting rack. The four detecting gun tubes are connected at the front end of the pneumatic telescopic slide table in parallel. The front ends of the four detecting gun tubes are respectively connected to conductive sponges. The leakage point counter is in series connection among the conductive sponges and the pipe rack by a detecting wire so as to form a conducted detecting loop. The detecting device is similar to a resistance detector and is very sensitive to resistance of an insulated coating and a water injecting needle hole. If needle holes are met, water in the conductive sponges penetrates into the needle holes, the current is conducted and a sound signal is activated, and therefore only the needle holes penetrating through the coating can be detected. By adoption of the detecting device and a detecting method, coating quality is not influenced, four pipes can be detected by one step, the average time for detecting each pipe only is 45 seconds, and the efficiency is high.