The utility model discloses a reliability test device of lathe power knife rest, concretely relates to electromagnetism and mixed loading knife rest reliability test platform of electric putter, overcome that prior art exists can't simulate the knife rest the operating mode of oblique lathe bed and can't carry out the loaded problem of three orientation knife rests by while blade block, form by knife rest support component, cutting force load parts, cutter arbor parts and moment of torsion load parts, the knife rest support component includes that X is to mobile unit, Y to mobile unit, the cutter arbor part is fixed on the power knife rest, the power knife rest is fixed on X is to mobile unit, the one side at the power knife rest is arranged to cutting force loading part, cutting force loading part includes that XY is to electromagnetism loading unit and Z to the electric putter loading unit, the dynamometer machine is connected with the power output shaft of power knife rest in the moment of torsion loading part. The utility model discloses press close to the in -service use state of knife rest more, have the commonality height, adjust easy, simple structure, small advantage.