Abstract: Initial geostress field is very important reference for engineering design and stability analysis of underground engineering.The geological structures are complex,and the roadway surrounding rocks are damaged seriously in Qianchang Iron Mine mining area.So,it is important to master the distribution rules of the geostress field in the mining area for better understanding of roadway failure and supporting design.3D numerical model taking into account the main fault and strata in the mining area is established by using the three-dimensional finite difference numerical calculation software (Flac3D),and simulates the geostress field in the mining area,analyzes the geostress characteristics in the whole mining area,geotectonic locations and the -480 m level.The results show that the geostress in the mining area is dominated by gravity stress and the stratification phenomenon of geostress is obvious and the value gradually increases with depth,the geostress is affected so seriously at the junction of geological structures and lithology that stress concentration phenomena of different degrees occur;the tectonic stress of F1 fault has relatively great influence on -480 m level main haulage way;the lateral pressure coefficient of -480 m level main haulage way is 0.46-0.58,the angle between the maximum horizontal principal stress and the direction of the roadway is 2.60°-47.75°,which is unfavorable to maintain stability.In order to reduce the influence of geostress field on the stability of roadway,it is suggested that the layout of underground roadway should follow the principle that the direction of roadway is parallel to the direction of maximum horizontal principal stress.