Abstract: Calculation of accessibility of casing going through well bending section is an important way to judge whether a casing is capable of going through a well bending section before the actual casing going-down operation.Using the analytical method and the finite element method(FEM), the accessibility of non-API casing going through well bending section is analyzed and calculated.It is shown that the results of the analytical method and that of the FEM are basically the same.The analytical calculating formula can meet the requirements of the field and provide theoretical support for the going-down operation of non-API casings.