Through analyzing the causes and damage of the fouling in water channel of water cooling engine, this paper develops a new kind of compound cleaning and descaling agent and conducting polyaniline corrosion agent of the water tank. This new cleaning agent is stable and harmless, and can be added to the cooling system directly without the special equipment. With the circulation of the coolant, the agent can remove the scale, and then the removed scale flows out of the auto with the coolant. Except for this new cleaning agent, the antiseptic, whose major agent is the conducting polyaniline, can decrease and even stop the corrosion of the water tank and cooling system’s parts, and at the same time, the formation of the scale can also be restrained notably. When the agent is in use, it can be added(press 1% ratio to join) wholly into the water port, or complemented at any time, so that the quick cleaning and the anticorrosion are realized without disassembling and corroding the engine. By using these agents the cleaning efficiency of the engine cooling system is improved, the favorable engine’s technology situation is kept, and the engine’s life-span is also increased efficiently.