Abstract: In order to decrease the simulating time and getting more scale of simulation model, this article implements a parallel TOUGH2-ECO2N on OpenMP. Through the time-consuming assessment, the main time-consuming part of this simulator is the thermophysical properties and phase diagnostics calculation, mass and energy balance equation setup and linear equations solving. Based on it, following the principle of OpenMP parallelism, the parallelization of multiphase flow simulator was accomplished by using dynamic memory allocation, handling jump statements and correlation within algorithm, internal parameters of function, and so on. The experimental results show that the parallelization simulator has the characteristics of correctness, high efficiency and improve the process of solving the multi-phase simulation model.For small and medium scale of simulation model comparison test, the speed was increased by 2.28 times.