The shale gas desander often has erosion failure, and its effect of removing sand is not ideal, especially for small-size sand particles, which leads to a large number of sand particles entering the pipeline and increases the risk of failure of the pipeline, posing a great threat to shale gas production. To solve this problem, a novel desander was designed based on the existing desander of the Changning area and FLUENT software. Moreover, the structure of the desander was optimized (inlet aspect ratio, cylinder diameter ratio, and cone diameter ratio), and the effects of different velocities and sand particle diameters on the amount of erosion wear and separation efficiency were studied. The results show that the optimal inlet aspect ratio, cylinder diameter ratio, and cone diameter ratio are 2.5, 1.5, and 2, respectively, and the maximum erosion rate is only 3.54 x 10(-9) kg/(s center dot m(2)). When the inlet velocity is lower than 10 m/s, the annual erosion thickness is less than 20.6 mu m, and when the particle diameter is larger than 20 mu m, the separation efficiency is above 88.1%. This greatly improves the separation efficiency of the desander and reduces erosion wear, ensuring the safe operation of shale gas production.