The invention discloses a detecting tool which comprises constant temperature equipment, a
refrigerant heat dissipater, a heating module, a flowmeter, a first temperature sensor and a first temperature sensor
assembly, wherein the constant temperature equipment is provided with an inlet and an outlet, and is constructed to enable the temperature of cooling liquid flowing out of the outlet to be constant, the
refrigerant heat dissipater comprises a heat dissipating
pipe and a heat dissipating body, one end of the heat dissipating
pipe is connected with the inlet through a first pipeline, the other end of the heat dissipating
pipe is connected with the outlet through a second pipeline, the heating module comprises a heating body used for generating heat, the heating body is arranged on the heat dissipating body, the flowmeter is arranged between the constant temperature equipment and the
refrigerant heat dissipater and used for detecting flow of the cooling liquid flowing out of the outlet, the first temperature sensor is arranged on the first pipeline and used for detecting the temperature Ta of the cooling liquid in the first pipeline, the first temperature sensor
assembly is arranged on the second pipeline or the heat dissipating pipe and used for detecting the temperature Tf of the cooling liquid after heat exchange, and
thermal resistance theta of the refrigerant heat dissipater is equal to (Tf-Ta) / P, wherein P represents power of the heating body. The detecting tool can detect the
thermal resistance of the heat dissipater.