The bending curve of flexible plate was calculated by numerical integral method at the specified bending moment and shearing force， based on the deflection equations of beams according to the mechanics of materials. The length of plate was also derived by line integrals in the meantime. Then the bending curve， moment and shearing force can be finally determined relative to the given length and span. The finite element software was employed to simulate the same model under the same conditions. Compared to the results of finite element method， it is found that the bending curves by numerical calculation were almost identical， in addition， the precision of the moments and forces can meet the practical demand in engineering. All the parameters of bending plate can be used for further analyzing and estimating based on the above numerical calculation method， which is valuable for guidance in the practical engineering applications.