Abstract: In order to find the early cracks of steam turbine blade, 2Cr12NiMoWV stainless steel was taken as the research object. A kind of hand-held probe by using eddy current technology was designed and its performance in different crack depth and crack width was studied. At the same time, COMSOL Multiphysics was used to carry out finite element analysis. Experimental results show that compared with the change of defect width, the device has higher sensitivity to the change of defect depth, which provides theoretical basis and technical support for the subsequent online hand-held eddy current sensor nondestructive testing of complex surface.