To study the error of calculated stress results and real measurement values of the cantilever beam with different element types and the its influencing factors, firstly, ABAQUS finite element software was used to model the shell element and solid element, and the stress value of Mises was calculated. Then the classical mechanics of materials method was used to calculate the same cantilever beam under Mises and the resistance strain test method was used to calculate real cantilever stress values. Finally, the shell element and the solid element of different thickness of the cantilever beam were used to calculate the Mises stress value. The results show that the Mises stress value calculated by the solid element is more close to the true value than the shell element. With the increase of the thickness of the cantilever beam, the accuracy of the calculation results of the shell element is getting smaller and smaller. For the same thickness of the cantilever beam, the relative error of the calculated stress value of the shell element at different position of the shell element is a constant.