The invention provides a frame torsional fatigue test bench with a loading device, and belongs to a test bench for automobile part assemblies. The frame torsional fatigue test bench comprises a portal frame, two actuators, a torsion beam and the like, and is characterized in that a front simulated suspension, a rear simulated suspension, a subframe and a frame are installed according to the state of an actual automobile; the upper end of the loading device is installed on the subframe to load, the lower end of the loading device is connected to jacks and spiral springs, the spiral springs can generate bidirectional displacement deformation along with movements of the frame, and follow-up movements of the loading device and a connection part of the frame are ensured; and the jacks are connected with the loading device through a lever so as to transfer a load carrying force, and the torsion beam and the spiral springs are fixed. The frame torsional fatigue test bench can comprehensively evaluate the torsional reliability of a frame assembly, actual working conditions are simulated through the bench device, and a follow-up constraint problem between the frame and a finished automobile mass loading unit is solved by the simulated loading device, thereby enabling the conclusion of a frame torsional fatigue test to have more reference values. The frame torsional fatigue test bench is novel in structure and effectively solves a problem of difficult evaluation for a durability test in development of a heavy commercial vehicle frame assembly.