Abstract: This application relates to a hard-shell inclusion strain gauge for 3D stress in surrounding rockmass of underground engineering. The hard-shell inclusion strain gauge comprises an elastic cylinder and at least three sets of strain rosettes, wherein the elastic cylinder is installed in a borehole of underground engineering, and at least three sets of strain rosettes are equidistant along the circumference on the inner wall of the elastic cylinder. It can accurately measure strain values and variables of each strain rosette through data collection and transmission module, and calculate 3D stress in surrounding rock of underground engineering. It can obtain dynamic long-term monitoring of 3D stress evolution in complex environments of underground engineering, truly reflecting the real-time state, the spatial distribution, and the evolution of 3D stress in rockmass, and provide in-situ basic data for engineering disaster warning and control.