Abstract: As a new numerical analytical method,fast lagrangian analysis of continua which appeared in 1980s',has been used in various fields,such as slope engineering,retain wall,supports of surrounding rocks and so on.In this paper,it is applied to predict the height of water conducted zone under sub-level caving method.As an example,the height of water conducted zone about 1303 sub-level caving in Xingji coal mine is obtained through simulation analyses,based on changeable characteristics of the stress and failure conditions after caving.This method is proved to have more advantages in comparison with other numerical methods.