Impinging stream reactors have been widely applied in industry with the advantages of efficient mass transfer and strong interaction between phases. Based on the traditional impinging stream reactor, a novel two-way accelerating tube coaxial opposing impinging stream reactor was constructed. The flow field mixing characteristics simulation was carried out in the reactor with air as the continuous phase and liquid water as the discrete phase. The high-speed gas?liquid mixed flow process at different gas flow rates was analyzed. Moreover, the changes of velocity, pressure distribution, particle diameter and stagnation time in the internal flow field were explored. The results showed that the flow field distribution was symmetrical above the impact surface, and the pressure and velocity at the stagnation point fluctuated most violently. With the increase of initial gas phase velocity, the flow field velocity rose slowly, then decreased slowly, and finally decreased sharply, and the pressure in the flow field decreased slowly, then increased slowly, after increased sharply and gradually coincided in the form of the double peaks of M-type. In addition, the pressure value at stagnation point increased non-linearly. When the initial gas velocity uout=30 m/s and uin=15 m/s, the velocity and pressure gradient of impact region were the largest, the turbulent kinetic energy was the strongest. Furthermore, the average diameter of the droplets in the new reactor was smaller and the residence time was longer, which were obviously superior to traditional reactor.