Select Measure Inertia .
Click Customize... in the Measure Inertia dialog box. The Measure Inertia Customization dialog box is displayed.
In the Measure Inertia Customization dialog box, select Principal axes check box
Click Apply. The Inertia / G tab in the Measure Inertia dialog box becomes available.
Click the Inertia / G tab to display the principal axes about which inertia is calculated.
Note: If you checked the Keep Measure option, bounding box values are also displayed in the specification tree
You can create the axis system corresponding to the principal axes.