Abstract: At present, the gas replacement process is difficult to monitor. Most of the parameters such as gas supply pressure and replacement time need to be calculated from personnel experience, which will cause a waste of resources and potential safety hazards. In this paper, a dynamic simulation model of gas pipeline network replacement process is established. Based on the one-dimensional topological network algorithm, the resistance coefficient in the pipeline network is accurately solved. Firstly, the horizontal straight pipe structure is established, and the correctness of the algorithm is verified by Fluent. Then the law of gas replacement process is analyzed and summarized. At the end of this paper, the model is applied to a gas pipeline network replacement project and compared with the actual measurement data. The calculation results show that the accuracy of the model proposed in this paper meets the requirements, and can provide an important guiding basis for the formulation of gas pipeline network replacement scheme.