Accurately assessing energy flow is of paramount importance for achieving the dual objectives of economic efficiency and energy efficiency in the operation of electric-thermal integrated energy systems. The generic thermal network model is commonly used to describe operating characteristics under baseline conditions. However, due to the high-dimensional nonlinear nature of solving its parameters, traditional methods have limitations. In this study, to address this issue, we conduct dual-mode detailed simulation analysis for the hydraulic and thermal processes of the thermal network. The finite difference method is employed to calculate dynamic parameters. Based on this, a network loss model is constructed using the mean square deviation method. To achieve the dual objectives of integrated energy system operation optimization, the NSGA-II algorithm and VIKOR decision rules are applied to obtain the optimal solution. Using these methods and taking a specific electric-thermal integrated energy system in the northern region as an example, we simulate and analyze the data of the system operation under three thermal network modes. The results indicate that the refined thermal network model can reduce the total operating cost to $16,871 and achieve an energy efficiency of 83.219 %, outperforming the results of other operational modes.