Gas-solid injectors are a power source of particles in pneumatic conveying systems. The momentum and energy exchange between particles and the flow field occurs for the first time in a gas-solid injector. The structural parameters of gas-solid injectors have a direct impact on the state of motion of particles. In the previous experimental study [1], we obtained the optimal structural parameters of a gas-solid injector under experimental conditions. However, there were many problems, such as the high cost of experimental equipment, high consumption of human and material resources, and long experimental time. In particular, the amount of reference data obtained from the experiment was limited, and the experimental results had certain manufacturing, human and accidental errors. Therefore, in this paper, the CFD-DEM coupling method is used to simulate the structural parameters affecting the performance of gas-solid injectors. The ejection ratio, energy consumption ratio, residue particle mass, particle outlet velocity, particle conveying ratio, percentage of total particle energy and total energy consumption ratio are adopted as the corresponding indicators to explore the relevant evaluation parameters that are difficult to obtain by experiment. The optimized structural parameters of the gas-solid injector under the corresponding indicators are obtained, which provides a design reference for the gas-solid injector and pneumatic conveying system under different working conditions. • Evaluation indicators obtained by CFD-DEM are difficult to obtain experimentally. • Optimal structure parameters are obtained under different evaluation indicators. • Nozzle length has the most significant effect on ejection performance. • Residual particle mass should be taken as primary indicator to avoid blockage. • Energy consumption should be taken as important indicator to improve efficiency.