Abstract: Taking the steam generator tube of CPR1000 nuclear power unit for example, regarding the issue of denting on the upper part of tubesheet caused by hard sludge which might induced stress corrosion cracking in steam generator tubes, this paper used three different types of eddy current probes to study the composite signal of denting with defect. Experimental results revealed that denting would impact on the detection of crack in the composite signal. When the depth of crack increased to 40% wall thickness in the composite signals, Bobbin probe showed significant changes in signal characteristics and MRPC probe could detect it effectively. Array probe would be better to detect the composite signals of local small denting with 20%T crack. Compared to the three types of probes, array probe had better detection ability for composite signals of denting with crack.