The invention discloses a large-tonnage vertical tension and compression universal testing system and a work method thereof, and belongs to the technical field of mechanical measurement and detection.The system adopts a main structure, which comprises four columns, an upper crossbeam, and a lower crossbeam. The upper surface and lower surface of the upper crossbeam are both provided with threadedholes for the installation of a large-tonnage high pressure center-hole jack. When the center-hole jack is arranged below the upper crossbeam, under the assistance of a high precision force sensor and a pressure head, a compressing and bending test can be carried out between the pressure head and the lower crossbeam. When the center-hole jack is arranged above the upper crossbeam, under the assistance of the high precision force sensor and different clamps matched with different samples, a tensile test can be realized. Four columns are provided with threads and nuts, can bear a load, and arecapable of adjusting and fixing the positions of the upper crossbeam and the lower crossbeam so as to change the space for tests. The system is suitable for samples with different sizes and tests in different forms. Through a high pressure oil pump, manual loading is realized, and programmed controlled loading can be realized under the assistance of a controller and a computer.