Abstract: Surface mining engineering is a scattered input-output systern. And its reliability is subjected to various stochastic factors, which can be effectively solved by simulation method. Based on reliability theo-ry and operation facts in flat-bedded open pit mines,the authors have given a new concept of surface mining engineering reliability measurement, which is used to evaluate the reliability of the designed or scheduled in-dexes and actually finished indexes,and set up the mathematical models for the system simulation of surface mining engineering reliability.