Aimed at optimizing the structure of jet-mixing apparatus, effect of three main structure parameters: nozzle-tube distance, area ratio and entrainment angle on the mixing performance were investigated based on CFD technique. A mathematical model for jet apparatus was established and validated by actual experimental data. Simulated results and experiment results showed that the established model was reasonable. The results indicated that nozzle-tube distance, area ratio and entrainment angle would not change the tendency of h—q with the increasing of flow ratio. However, both nozzle-tube distance and entrainment angle would not change the tendency of η—q except for area ratio.