Aiming at the deficiencies of the traditional uniform electromagnetic detection probes which is not suitable for the stainless pipe inner detection, a Helmholtz coil-type inner detection probe for stainless steel pipe and its experimental system are proposed and built. Through the finite element software Comsol, the finite element model of the uniform electromagnetic in the axial crack in stainless steel pipe inner detection is established, the distribution and variation law of the electromagnetic field in the pipe are explored, the characteristic signals Bx and Bz are selected, and the influence of the length and depth of the crack on the characteristic signal is analyzed. Based on the results of simulation and the characteristics of the inner detection in the pipe, the Hemholtz coil-type pipe detection probe is designed and a stainless steel pipe inner detection experimental system is built. The experimental results show that the detection system can realize the full circumferential scan of the axial crack on the inner surface of the stainless steel pipe.