Many tubular heat exchangers have been put into service in thermal power plant, such as boiler's air heater, turbine's condenser and so on. They are often polluted by medium, which result in scale on the inner wall of tubes and severely influence the normal operation. In order to increase the efficiency of tubular heat exchanger, the scale must be cleaned off in time. This paper presents a new-type equipment with which to clean tubular heat exchanger with high-pressure water jet. The sketch of the cleaning system is shown. Also, calculating equation of cleaning nozzle, jet's diameter velocity and force are given. In addition, this paper has given the experimental results of cleaning boiler's tubular air heater, with this equipment in thermal power plant. The results indicate that this equipment is simple in structure and has a high efficiency that is 20-30 times as high as conventional ones. This equipment is practical and efficient in cleaning tubular heat exchanger.