提出了一种比较精确且又省时的质子穿透的解析算法 ,并给出了考虑核反应后 5 0— 2 5 0MeV质子在水中的能量沉积 ,与Monte Carlo方法的结果进行了比较 .结果表明 :1)非弹性核反应对质子的能量沉积有明显的影响 ,特别是对较高能量的质子束入射情况 ;2 )该方法计算效率比MonteCarlo方法高百倍以上 .因此 ,本文方法解决了质子能量沉积计算中效率和精度之间的矛盾 ,有可能在质子束放射治疗中得到实际应用 A more accurate and time-saving analytical solution of proton penetration is proposed and the energy deposition of 50 0-250 MeV protons in water after nuclear reaction is given, which is compared with the Monte Carlo method. The results show that : 1) The inelastic nuclear reaction has a significant effect on proton energy deposition, especially for higher energy proton beam incidence; 2) The method is more efficient than the Monte Carlo method by a factor of 100. Therefore, the proposed method solves the problem of proton energy deposition The contradiction between efficiency and accuracy in calculation is likely to be put to practical use in proton beam radiotherapy