本文从传统冲击因子的不足出发，提出了改进型冲击因子的计算方法，利用某水下目标的抗水下爆炸试验数据，计算了不同工况下的冲击因子，结果表明该冲击因子能较好的反映目标的毁伤情况，利用估计的冲击因子临界值，计算得到了目标的损伤距离曲线。最后引入概率统计的分析方法，通过蒙特卡洛方法模拟得到了爆炸点在平面内变化时目标的毁伤概率。

In this article, on the base of traditional impulsive factor’s limitation, the method to calculate the modified impulsive factor is proposed. The modified impulsive factor in different case is calculated by using experiment data of a underwater target bombed by underwater explosion Results show that the target’s damage state can be reflected well by the modified impulsive factor. The target’s damage distance curve is obtained by the estimated critical value of impulsive factor. Then, the measurement of probability and statistics is introduced, the target’s invalidation probability with the explosion centre changing is given by the program of Monte Carlo simulation.