Effects of different gaseous nozzle injections on gas-solid dynamic mixing in FCC riser are experimentally studied by calculating the time fractions of the proposed phases (gas, diluter/denser dispersed particles, and cluster). Generally, a more dispersed particulate phase can be obtained when jets are downward. By analyzing the effects of operating parameters, it is shown that the larger jet/prelift flow momentum ratio increases the proportions of the gas and cluster phases, and the proportion of the useful denser, dispersed particulate phase decreases accordingly when nozzles are upward. For the downward pointed jets, the momentum ratio only affects the radial time fraction distributions of different phases. The cross-sectional time fractions of each phase change little with momentum ratios, indicating a good operational flexibility. To obtain better gas-solid dynamic mixing, suitable setting angle of nozzles is 30-45 degrees when nozzles are mounted downward.