Abstract: Longqiao Iron Mine is in the stage of transition from mining to caving.In order to ensure the stability of deep caving，the distribution law of ground stress below the -420 m section of Longqiao Iron Mine was studied by the method of hollow package body strain through field tests.The results of the study show that the maximum principal stress at the 1#to 6#measuring points of Longqiao Iron Mine is 15.20 MPa， 17.13 MPa，17.47 MPa，19.98 MPa，23.58 MPa and 21.72 MPa respectively，and the maximum principal stress is generally close to the horizontal direction.The maximum principal stress at the western area of the -437.5 m and -472.5 m sections is greater than that at the eastern area，while the opposite is true at the -490 m section，the maximum principal stress at the western area is less than that at the eastern area，and the area with the maximum principal stress is located at the western area of the -490 m section，with the maximum principal stress value of 23.58 MPa.The original rock stress of Longqiao Iron Mine increases con ⁃ tinuously with the increase of burial depth，among which the -490 m section has a greater increase com ⁃ pared with the -472.5 m section，indicating that the value of ground stress in the mine area is greater than the self-weight stress of the overlying rock and soil，which belongs to medium high ;the ground stress field in the mine area is also affected by the geological structure，rock type and the shape of the ore body and other factors.According to the distribution law of ground stress，corresponding measures are put forward to provide the basis for the safe production of the mine.

Key words: ground stress, maximum principal stress, stress relief, stability