Abstract: In order to solve the problem of Bobbin probe inspection blind spot in condenser tube sheet region, using the MRPC probe to inspect the tube in this region is introduced in this thesis. Through experimental study, different kinds of defects are distinguished and their signal characteristics are achieved. By setting up depth-phase curve, defect depth sizing is realized. To test the effectiveness of this inspection method, defects in the simulation test blocks of tube sheet are inspected and good performances are showed in probability of detection and depth sizing which is similar to the real depth.