In the Open dialog box, select the .dwg file that does not contain Autodesk Inventor data, and then click Options.
When you select a .dwg file that does not contain Autodesk Inventor data in the Open dialog box, you can:
Drawing Settings
Opens the file with full visual fidelity. All Autodesk Inventor data creation commands are available.
Imports and translates AutoCAD data into Autodesk Inventor.
Use the Application Options to specify a default value: