本文通过分析水流反冲力的作用，建立了旋转喷水龙头的运动微分方程，确定了临界喷射角和临界流速，证明系统唯一的定常运动是大范围渐近稳定的；在此基础上，给出了水龙头灌溉区域的形状和面积计算公式；最后讨论了水流周期性脉动的影响.

 By analyzing the dynamic reaction force of water flow，the motion differential equation of the rotary watering sprinkler is established. The critical ejection angle and the critical flow velocity are determined，and it is proved that the unique steady motion of the system is asymptotically stable in a wide range. On this basis，the shape and the irrigation area of the sprinkler are given. Finally，the influence of periodic water flow pulsation is discussed.