The validity of numerical simulation of initial ground stress has very important effect on the dependability of calculated results for the numerical simulation and analysis of stability of underground excavation engineering.The simulation of initial ground stress is realized mainly by boundary conditions of calculation model.As for non-uniform horizontal ground stress,it is realized generally by applying non-uniform pressure load on the lateral boundary/boundaries of the calculation model.However,it is found that there is a certain relationship between simulated result of non-uniform horizontal ground stress and geometrical shape of calculation model: the greater the width to height ratio of the calculation model is,the more unsatisfactory the simulation validity is and the greater the difference between practical ground stress and simulated stress is.At the end of this paper,two methods are given out to solve this problem:(1) to decrease the width to height ratio of the calculation model,make it not greater than 1;(2) to restrict horizontal displacement of lateral boundary/boundaries and to directly assign ground stress in the field of calculation model.