The gas-solid injector is the power source of the particle pneumatic conveying system. The injector structural parameters have a large impact on the pneumatic conveying system. To obtain the optimal structural parameters of the injector for large particles, the injection ratio in the pure flow field experiment (PFFE), the average static pressure of stable conveying (pressure index) and the particle transport time (time index) in the particle injection experiment (PIE) are used as the performance indexes. The influence of the structural factors on the injection performance in the PFFE and the PIE are obtained by the multi-index orthogonal test scheme. The optimal structural parameters of the injector in the PFFE and the PIE are compared and verified, providing significant guidance for practical applications and an experimental basis for the large particle pneumatic conveying system. (C) 2019 Elsevier B.V. All rights reserved.