Abstract: When the welded joints of heat exchanger (Ti) and tube-plate (Ti/steel composite plate) are tested, there are many problems such as the difficulty of removing the permeate from the inner wall of the tube hole, and many other problems. A special tool for the removal of the penetrant is made through many technological practices. Combined with the comparison of three kinds of osmotic testing materials, the suitable removal process and testing materials were finally determined, and good results were obtained. The results provide a reference for the penetration detection of similar products.