The invention relates to a large-ramp ballast track bed stability evaluation method, aiming at objectively analyzing the stability problem of the large-ramp ballast track bed under extreme conditionsunder the combined action of train load, temperature load and gravity, more conforming to the actual engineering condition, and providing technical reference and theoretical support for paving a ballast track in a large-ramp mountain area section. The method comprises the following steps: (1) establishing a large-ramp ballast track nonlinear finite element model, and modeling by adopting a parameterized design language (APDL) of finite element software ANSYS, including a steel rail, a sleeper and a ballast bed structure; (2) analyzing the stability of the ballast track bed of the large-ramp railway, applying a train load, a gravity load and a temperature load to the established nonlinear finite element model of the large-ramp ballast track, and solving according to the slope and vertical curve radius working conditions which need to be set; if the finite element calculation is not convergent, indicating that the ballast bed is damaged, and entering an unstable state; otherwise, indicating that the ballast bed is stable, and extracting equivalent plastic strain of the ballast bed to determine a dangerous area and a potential sliding surface of the ballast bed.