The accuracy of twodimensional model for calculating the contact stress of O-ring under the condition of eccentricity was studied.The finite element analysis software ABAQUS was used to carry out twodimensional and threedimensional numerical simulation analysis on the O-ring with eccentricity,and twodimensional and threedimensional calculation and comparison of contact stress were carried out under the condition of different O-ring diameters and different eccentricities.It is found that when the O-ring is eccentric,compared with the threedimensional model,the twodimensional model tends to have a larger contact stress at the maximum compression value,and have a smaller contact stress at the minimum compression value.Moreover,the increase of eccentricity and the decrease of O-ring diameter result in the increase of the calculation error of twodimensional model.The curves of contact stress error of twodimensional model with the change of eccentricity and O-ring diameter were fitted,and the prediction formulas of contact stress calculation error of twodimensional model were obtained,which can be used to modify the predicted value of contact stress of twodimensional model of O-ring.