Abstract: In this paper, the ultrasonic water immersion single probe reflection method was used to test the defects. According to the shape of the defect reflection wave and the position in the time domain the depth and type of defect were analyzed and evaluated. The homogeneity of the core distribution was tested by using the 59.5 keV ²⁴¹Am source. The thickness of the shell was analyzed and evaluated according to the relation between the thickness of shell and the change of eddy current impedance. The internal defect testing and evaluation of the plate fuel element through ultrasonic, ray and eddy current testing methods ensure the quality of the product.