The measurement of the inner surface of a hole part is an important means to judge its machining quality and service life.A method of measuring the inner surface and signal processing based on low coherent interference was proposed for the needs of measuring the inner surface of precision hole parts,and a complete inspection system was built.The measuring principle of low coherence interference was analyzed.A detection system based on Michelson interferometer was built,including light source,detector,data acquisition instrument,reference arm,measuring arm and so on.Then,interference signal filtering and envelope peak extraction algorithm were studied.Finally,it is experimentally verified that the system can characterize the internal features of hole parts and measure the internal diameter with an accuracy of up to 10 μm.