In the process of oil exploitation, sand-carrying fracturing fluid‘s erosion and abrasion law and main influencing factors of the wall of the variable diameter T-shaped flow channel are studied. diameter T-channel in oil fracturing manifold and down hole sandblasting tool. A CFD-DEM model for predicting erosion wear of solid-liquid two-phase flow in variable diameter T-channel was established. In this model, a reverse iterative collision search algorithm was adopted for particle-particle and particle-wall collisions, and the time step of particle-fluid coupling calculation was adjusted adaptively according to the coupling convergence conditions. The interaction between the mean main effect response and the change of each factor and the priority of each factor change were analyzed by the combined numerical method and orthogonal test method, and the influence of the change of single factor of erosion method was also studied. In univariate analysis, the maximum erosion rate and erosion area of the T-channel increased with the increase of inlet velocity, and the erosion location moved towards the outlet of the channel. The particle carrying capacity of the fluid increased, and the amount of accumulated particles decreased. In the sand ratio range of 5%~35%, the maximum erosion rate is positively correlated with sand ratio. The maximum erosion rate increases first and then decreases with the change of particle size, and decreases with the increase of diameter ratio. The results are consistent with the main effect analysis of the mean maximum erosion rate, which verifies the accuracy of the orthogonal experiment conclusion. When radial velocity, tangential velocity, pipe wall pressure and maximum erosion rate are the indexes to measure the erosion degree of variable diameter T-channel, inlet velocity has the greatest influence, followed by proppant particle size, variable diameter ratio and sand ratio. The interaction between inlet velocity and other factors has the most significant influence on erosion rate.