In order to solve the problem of the performance of mixed alkane phase change energy storage materials, this paper proposes the modelling research of mixed thermodynamic model based on new materials. In this paper, the thermodynamic performance of binary mixed alkane system is studied, the influence of phase transition temperature, phase transition enthalpy and its composition on the mixed alkane system is explored, and its solid-liquid phase diagram is drawn. We used different thermodynamic models to predict the phase transition temperature and enthalpy in the melting process of binary mixed alkanes, which were mutually verified with the experimental results. The experimental results show that C9-C10 and C9-C11 systems exhibit eutectic behavior. The eutectic components are 88% (mass fraction, the rest is the same) C9-12% C10 and 90% C9-10% C11. The eutectic temperatures are 218.25 K and 215.15 K, respectively. The C8-C9 system has peritectic phenomenon, C10-C11 system shows complete mutual solubility, and their mini­mum melting points are 200.25 K and 234.35 K, respectively. Conclusion is that the C9-C10 and C9-C11 eutectic systems are suitable for low temperature phase change materials in the temperature range of 210-220 K, providing data reference for their application in low temperature energy storage.