Abstract: As a kind of clean and green energy, natural gas accounts for an increasing proportion in global energy consumption structure. So far, a large number of studies were carried out on the optimization of natural gas supply chain, but most of them focused on the optimal demand allocation of single supplier, while few study was conducted on the optimization of natural gas supply chain in multi-competitive market. For the competition between two suppliers for the same market, the maximum profit of the two suppliers was taken as the objective function, and with consideration to the constraints of balance between supply and demand, as well as the construction of pipeline, station and gas storage, the mixed integer quadratic programming(MIQP) model and the mixed integer linear programming(MILP) model were respectively developed for the two suppliers, which were solved through particle swarm optimization(PSO) algorithm. Additionally, by applying the models to a natural gas supply chain system in the coastal region of China, the gas supply scheme and construction scheme of each supplier were worked out. The calculation results show the applicability of the model and the good stability of its solution, and the research findings are of guiding significance for optimizing the natural gas supply chain with the market competition considered and ensuring the economy and stability of natural gas supply.