The thermo-physical properties of molding materials for sand casting depend on changes in the composition of binders under thermal action on the technological equipment made from sand-based mixtures. We present the results of developing an algorithm for modeling the thermo-physical properties of molding materials used in sand casting. We used the solution of the inverse problem of heat conduction by the Levenberg - Marquardt method which suggested using iterations to the results of solving the direct problem of calculating the non-stationary temperature field. The direct problem of the nonlinear thermal conductivity upon solidification of a casting in a sand mold was solved using the LVMFlow program. Data on the temperature field during solidification of the AK7 alloy casting in a sand mold were obtained using thermocouples. The accuracy of temperature measurements with thermocouples was assessed in relation to sand casting processes depending on the casting dimensions and the melting temperature of the casting alloy. Thermocouples with chromel-constantan electrodes are recommended for the experimental determination of temperature fields in aluminum alloy castings. The proposed algorithm is intended for processing data on temperature fields measured by thermocouples upon solidification of castings in a sand mold and calculated by simulating the identical casting process in the LVMFlow program. The developed algorithm is implemented in the SciLab software environment and ensures the correct construction of the Jacobian matrix. The results obtained can be used in computer simulation of casting technology, taking into account the thermo-physical properties of mold materials, which reduces the time spent for the development of technological processes and equipment.