A file with an ".ai" file extension is an Adobe Illustrator vector graphic drawing, so you can open it using the Adobe Illustrator program. However, the AI file is really just a Portable Document Format, or PDF, file with the AI file extension. To convert a PDF to an AI file, simply change the PDF file extension, or ".pdf," to the AI extension, or ".ai." To convert another type of file, such as an Adobe Photoshop file, or ".psd," use the Photoshop application to export the PSD file as an AI file.
Rename a PDF File Extension to AI
Right-click on the Windows "Start" button and click "Open Explorer" to open Windows Explorer.
Click "Tools" from the top navigation menu, then click "Folder Options."
Uncheck the option labeled "Hide File Extensions of Known File Types" and click "OK." File extensions are now displayed along with file names.
Right-click on the PDF file and click "Rename."
Scroll over the file extension portion of the file name, or ".pdf," and type ".ai" as the new file extension.
Right-click on the AI file and click "Open With." Click the "Adobe Illustrator" option from the list of available programs to open the file in Adobe Illustrator.
Save As AI File in Adobe Photoshop
Create a graphic to be exported to Illustrator in Adobe Photoshop.
Click the "File" option from the top navigation menu, then click "Export." The Export File window opens.
Click the "File Type" drop-down list, then click the "Adobe Illustrator (*.ai)" option.
Click the "Export" button. The Adobe Photoshop file is exported as an Adobe Illustrator file.