Hello nilsubozan,
When you import pictures from the phone to the computer, it's only going to import whatever pictures are new. It will not re-import pictures that were already imported to the computer.
Transfer photos and videos from your iPhone or iPad to your Mac or PC
If you've completed the import and you're missing pictures on the computer that are currently showing on the phone, you'll want to make sure you currently have those pictures stored on the phone and not in iCloud through the iCloud Photos service. You can check in Settings > name at the top > iCloud > Photos to see if that is currently enabled or not. If it is, you'll need to turn it off so all the pictures store directly to the device first, then you can manually import them.
Alternatively, if you want your pictures to automatically sync across all devices instead of having to manually do it, turn on the iCloud Photos service on both the iPhone and the computer.
Set up and use iCloud Photos
Cheers!