The invention relates to a true three-dimensional loading model experiment system for highland stress, comprising an intelligent hydraulic control system, a high-pressure loading system and a counterforce device system, wherein, the high-pressure loading system is arranged in the counterforce device system; an intelligent hydraulic control test bed of the intelligent hydraulic control system is connected with the high-pressure loading system through a high-pressure oil pipe; the high-pressure loading system comprises a jack and loading plates; one end of the jack is connected with the loading plates; the other end of the jack is connected with the counterforce device system; and six loading plates connected with the jack respectively cling to front, rear, left, right, upper, lower side surfaces of a trial model. The system has the advantages of synchronous and independent highland stress loading, high loading automation degree and loading accuracy, more loading functions, the realization of the axial loading opening of a cavity, high rigidity of the loading system, good integral stability, simple and convenient operation and so on. The system can be widely used in deep underground cavity model experiment and research in engineering fields such as hydroelectric power, transportation, energy, mine, national defense and so on.