Abstract: An experiment for measuring subsidence Gaussian Curve was made and it has been found that the standard deviation of the Gaussian Curve (σ) varies as the original height of subsidence layer (z), that is, σ² = 1/2βz^α. From this and analysing the process of broken rock movement by means of the pellet filling into vacancy model, a probability equation of broken rock stochastic displacement is presented, which contains a parameter for adjusting the shape of drawn profile when ore drawing through a bottom hole. The meaning of parameters in the equation is discussed in detail, and the method for determining them is given. By use of the equation as its mathematical model, the computer simulation method in ore drawing is being improved and perfected. Two application examples of the simulation are introduced in the paper, and they can prove that new simulation method can satisfy the requirement for predicting the recovery of ore or coal and optimizing the construction of mining stope in caving system.