In order to effectively improve the accuracy of the numerical simulation, a new model for interfacial heat transfer coefficients （IHTC） is parameterized and modified. Based on this continuous IHTC model of three-step evolution, a new inverse method is proposed to evaluate IHTCs by combining the FEM numerical simulation with optimization calculation and measured temperature data dependent on position according to the nonuniformity air gap in the horizontal continuous casting. The numerical simulations of Sn-5Pb and Sn-15Pb alloys were conducted by the model. The results show that the simulated temperature is well in agreement with the measured temperature from three positions, and the maximum deviation is less than 5%.