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Forest fires happen frequently all over the world. Forest fires have the characteristics of wide range of influence, high fire intensity and difficult human rescue. Therefore, fire-fighting aircraft has become one of the most effective tools to deal with forest fires problems. How to get better fire-fighting effect has become a hot research problem. Based on the theoretical study of cylindrical jet atomization under transverse jet flow, this paper established a rapid water dropping prediction model by using the WAVE model of secondary jet atomization and particle dynamics method [1]. By using the VOF to DPM method in FLUENT, aircraft water drop models at different flight speeds and altitudes were constructed, and the process of column breakup and secondary droplet breakup is simulated. Secondly, the DPM particles after secondary breakup are simplified into droplets, and the position, velocity and diameter information of the droplets are input into MATLAB. According to different flight speed and altitude, the form of water drop, the covered area of water drop and the effective utilization rate of water drop are calculated and analyzed. Finally, the numerical results show a good agreement with the wind tunnel test results [2]. This research method can be used to calculate the water dropping form and water dropping distribution at different flight speeds and altitudes, achieving the optimal method to drop water，which provides a reliable strategy for realizing efficient and effective forest fire suppression.

fire-fighting aircraft;water dropping;VOF to DPM;fire extinguishing effect evaluation