Abstract: Under different maximum axial deformation conditions, the cylindrical metal test blocks containing U-shaped,V-shaped and rectangular prefabricated artificial defects were prepared by diffusion bonding method. The deformation of the block and prefabricated defects, interfacial fusion and the ultrasonic feedback were analyzed by laser 3D scanning, ultrasonic C-scanning, stereo light microscope and metallographic microscopy. The results show that the height and radial deformations of the cylindrical test block decrease with the decrease of the maximum axial deformation. The actual height deformation of the test block is slightly bigger than the maximum axial deformation, and the test block radial deformation shows an approximate "drum" shape with the middle high and the two ends low. The linear correlation level between the height deformation of U-shaped, V-shaped, rectangular prefabricated defects and the maximum axial deformation is rectangle＞U-shaped＞V-shaped. The deformation of the defect width is affected by the angle between the diffusion interface and the defect contour boundary, and the V-shaped defect has poor stability and large deformation.The interfacial fusion state under different maximum axial deformations is good, and the ultrasonic C-scanning results show that the prefabricated defects are obvious and the outline is clear, and there is no defect information due to poor diffusion bonding.