Abstract: The cleanliness of the condenser directly affects the heat transfer capacity of the condenser, and long-term operation of the condenser often results in sediment and biological deposits. For the seawater cooling units of a certain power plant, a marine-type condenser online cleaning robot was designed and successfully applied to a 300 MW unit condenser. By analyzing the operating parameters of the condenser before and after cleaning, the marine-type condenser online cleaning robot reduced the water resistance by 0.04 kPa and increased the vacuum by 1.01 kPa after the operation. The design can effectively improve the cleanliness of the condenser tubes and improve the heat transfer efficiency and efficiency of the condenser.