Abstract: At present, CO₂ immiscible displacement has become an important technical means to enhance oil recovery in the development of tight reservoirs. However, the strong heterogeneity of tight reservoirs leads to the problem of gas channeling in the process of CO₂ displacement. In order to solve this problem, the advantages of water flooding and gas flooding were combined by the CO₂ water alternating gas technology, and gas channeling was suppressed effectively. Therefore, based on the multi-relaxation time lattice Boltzmann method, coupled with the Shan-Chen multiphase multi-component model, the influence of different initial water saturation, water flooding front position, water-gas slug size and water-gas slug ratio on the dynamic occurrence law of multiphase fluid were discussed systematically in this paper. The results show that in the process of different types of water alternating gas, the flow resistance was affected by the proportion of injected water significantly, thus the displacement path of water phase and gas phase were changed. The specific performance is that the gas phase sweep range was expanded because of the discrete distribution of low proportion water slug, and the displacement efficiency was improved effectively, but there is still a certain risk of gas channeling. The high proportion of water slug can stabilize the displacement front, but the oil phase is limited. This paper reveals the microscopic percolation mechanism of CO₂ water alternating gas enhanced oil recovery in tight reservoirs, provides a scientific basis for the optimization of gas channeling parameters, and has important theoretical value and practical significance for guiding the efficient development of oilfields.