The measuring system generates a temperature difference between a heating terminal and a terminal conductive device by setting the temperature of a metal heated block at the heating terminal and the temperature of a heat dissipating water jacket at a heat dissipating terminal, and judges the thermal conductive capability of the thermal conductive device by comparing the cooling speed of the metal heating bock to obtain a relative power value according to the variation of heat quantity of the metal heated block in practical temperature reduction process. The maximum thermal conductive quantity (Qmax value) of the thermal conductive device can be rapidly obtained by parameter conversion with respect to the maximum power value. In the case of confirming the cooling curve (cooling speed) of a standard sample, the object of screening the thermal conductive efficiencies of the thermal conductive devices can be achieved by using the cooling curve.