Abstract: In order to have a geostress distribution law of a deep mine in Yima Mining Area, a geostress measuring method and device with the hydraulic fracturing in the small diameter borehole was applied to conduct 2D geostress measurements of 14 measuring points in 4 mines of deep mining areas in Yima Mining Area. The max depth of the measurement was 1 011 m. Based on the data measured at the mine sites, the deep geostress distribution drawing of Yima Mining Area was made. The deep in-situ rock stress obtained mainly as the vertical stress in Yima Mining Area was in the typical gravity stress field and there was big difference in the type of the stress field in the east part, west part and central part of Yima Mining Area. The max horizontal principal stress was 25.25 MPa and wholly the geostress value belonged to the high stress level. The max horizontal principal stress was concentrated in the direction of NNE and had a high consistency to the direction of the stress field in the regional block of Yima Mining Area. The relation between geostress and underground depth as well as the ratio relation between the average horizontal principal stress and vertical stress were established.