The consequent rock slope is a common type slope in engineering

and the flexural failure often occurs in construction of consequent rock slope.When the overlying rock mass meets the requirement of sliding

and the front of rock is hindered in sliding

it will cause the consequent rock plate near the foot to be under vertical compress stress.In addition

with the joint action of the seismic force and the hydrostatic pressure.It will be liable to cause flexural deformation until flexural failure.The article is based on the theory of elastic-plastic plate stability

considering the influence of plasticity of rock mass and slope length

and giving special considerations to the influence of seismic force and the hydrostatic pressure

and then establishes the computing formula of the length of flexural failure and the stability coefficient.After contrastive analysis between the computing formula and the existing analysis method

the consistency and the difference will be given.Combined with the special parameters of the Chongqing-Huaihua Railway’s two engineering projects and putting them into formula and then calculating with MATLAB

it finds that the results are consistent with the actual investigation.Besides

the influence of different parameters of seismic force and the plastic parameters of rock plate on the calculation results are analyzed

which verifies the feasibility of this method.