Abstract: This paper discusses the application of mechanical cleaning technology and its necessity in dome-roof oil tank.In consideration of the differences existed in mechanical cleaning technology for dome-roof tank and floating-roof tank, the installation method of jet should be different.For the dome-roof tank, the jet shall be installed on the top of the tank, and installation of it includes two types.one is made with the existing hole on the tank-top, and another is made with tapping on the tank-top, and if the jet installation location and jet quantity cannot satisfy the requirements of the cleaning operation, the jet can be installed on the tank wall near manholes.In the paper, the technical preparation procedure before tapping including the manufacture method of fixing support of jet, prefabrication of tapping adapter and technical key points of bonding with tank roof, installation of tapping machine, and safety measures of tapping operation, and other tapping operation technology is given, and the cautions in mechanical cleaning operation are provided.