针对边坡小概率破坏的高效模拟问题，提出采用方向模拟方法进行计算，介绍了方向模拟的基本理论和楔形体破坏功能函数的算法，编制了岩质边坡楔形体破坏概率的方向模拟的Matlab程序，分别将方向模拟结果与重要抽样模拟、子集模拟的计算结果进行了对比分析。结果表明，方向模拟与子集模拟一样适合于小概率破坏的计算，方向模拟方法在抽样次数较少的情况下就能获得较高的计算精度，与其他两种方法相比效率更高。

Directional simulation method is proposed to calculate the small probability of slope failure. Algorithms of directional simulation and wedge safety factor are introduced and programmed. The direction simulation results and the importance sampling respectively, compare the calculation results with the subset simulation analysis. The results show that the directional simulation method can be used to calculate the small probability of slope failure as the same with subset simulation method. And directional simulation method can get enough accuracy by a small number of sampling, which means more efficiency than the other two methods.