The invention discloses a multi-taper deep hole processing detecting device, which consists of a guide post, a lead screw, a fixing mechanism, a crawler, a motive power mechanism and a data processing system, wherein the lead screw is arranged on the fixing mechanism, the crawler is fixedly connected with the middle position of the lead screw, the guide post is arranged at the front part of the lead screw, the motive power mechanism is fixedly connected with the back part of the lead screw, the crawler with a sensor moves along the lead screw and collects data, the data is transmitted to the data processing system through a data wire, and the guide post, the lead screw and the fixing mechanism form a simple support beam structure. The detecting device is mainly used for detecting the dimension precision and the surface quality of multi-taper deep holes during precise processing. For the multi-taper deep holes, the detecting device can realize the self guide, various parameters of the multi-taper deep holes can also be simultaneously detected, and the function of detecting multiple data in one step is realized. The detecting device has the advantages that the structure is simple and practical, the advancing and the retreating of the detecting device are realized through mechanical transmission, the detection function is realized through a sensor, and the detection process is stable.