The utility model discloses a reliability test system of a heavy-type numerical-control vertical lathe and aims at overcoming a problem that current reliability test devices of heavy-type numerical-control vertical lathes are incapable of simulating dynamic or static cutting force or torque loading. The system includes a balancing weight inertia loading and loading assisting device, an electro-hydraulic servo cutting force loading device and a vertical dynamometer torque loading device. The balancing weight inertia loading and loading assisting device is installed on a rotating table in the heavy-type numerical-control vertical lathe. A radial electro-hydraulic servo loading device in the electro-hydraulic servo cutting force loading device is installed on the ground at the periphery of the rotating table. One end of the radial electro-hydraulic servo loading device contacts the circumferential surface of a loading table. The top end of an axial electro-hydraulic servo loading device is fixedly installed at the bottom end of a ram in the heavy-type numerical-control vertical lathe. The bottom end of the axial electro-hydraulic servo loading device contacts the upper surface of the loading table. The vertical dynamometer torque loading device and the loading table are fixedly connected with the center of the rotating table.