The invention belongs to the technical field of heavy machining equipment reliability testing and particularly relates to a heavy numerical control plano-boring and milling machine workbench feeding system reliability test bed. The heavy numerical control plano-boring and milling machine workbench feeding system reliability test bed solves the problem that an existing reliability testing device cannot conduct a loading reliability test simulating the actual working conditions on a heavy numerical control plano-boring and milling machine workbench feeding system. The heavy numerical control plano-boring and milling machine workbench feeding system reliability test bed comprises a balancing weight inertia loading and loading auxiliary device part, an X-direction loading part, a Y-direction loading part, a Z-direction loading part and an automatic control part. The X-direction loading part comprises a vibration exciter, a first tension and pressure sensor, an auxiliary loading workbench, a first X-direction loading rod, a second X-direction loading rod and a cover plate. Two sets of identical hydraulic loading devices serve as the Y-direction loading part. The Z-direction loading part comprises an electro-hydraulic servo loading unit. The automatic control part comprises an upper industrial personal computer, a PLC, a vibration exciter controlling instrument, a Y-direction servo controller, a Z-direction servo controller, a servo controller in the moving direction of a workbench and a servo controller in the moving direction of an auxiliary workbench.