Abstract：The change of in-situ stress field due to underground mining of metal ore has often resulted in major disasters in the metal mines. Stress change not only influences the stability of the deep tunnel，but also changes the range of rock mass displacements due to mining. Based on the results of numerical analysis for a large amount of measured results of in-situ stress in metal mine，the fundamental theoretical formulas of in-situ stress in horizontal and vertical direction are given. The results of the numerical analysis show that the in-situ stress，the range of rock mass displacements and deformations in overlying strata increase with the increment of depth of underground mining. The influence of the tectonic stress in the horizontal direction on range of rock mass displacements is evident，which is very important for deep underground excavation activities，especially for the metal ore mining.
