The invention relates to the technical field of seawater circulating cooling water treatment and particularly relates to a performance evaluation device and method for a seawater circulating cooling water treating agent for a chemical system. The device comprises a water replenishing unit, a heat exchange unit, a cooling tower unit, a pollution discharging unit, a dosing unit and a monitoring unit. The device is characterized in that the monitoring unit comprises a corrosion monitoring unit arranged on a circulating water pipeline of the heat exchange unit; and the heat exchange unit comprises an analog monitoring heat exchanger (15), a steam condenser (16) and a boiler (18). By using the whole set of device, the online monitoring on a plurality of seawater circulating water treatment process parameters (temperature, flow rate, pressure, pH value, conductivity, corrosion rate, fouling thermal resistance and the like) and automatic control on a plurality of tasks (dosing, pollution discharging, water replenishing, liquid level, water balance and the like) can be realized, and a more effective hardware supporting platform is provided for the research, development and industrial application of a novel seawater circulating cooling water treatment technology.