According to the theoretical basis of thermo-kinetics, a novel thermo-kinetic research method, the time-parameter method for reversible reactions, has been proposed in this paper. The rate constants of forward and backward reactions and equilibrium constant can be calculated from the same thermoanalytical curve simultaneously with this method. In order to test the validity of this method, the proton-transfer reactions of nitroethane with ammonia at 15 and 25 degrees C, and with Tris at 15 and 30 degrees C have been studied, respectively. The results of rate constants and equilibrium constants calculated with this method are in agreement with those in the literature. Therefore, the time-parameter method for the reversible reaction is believed to be correct.