Move your iTunes library to another computer
Important: It’s recommended that you create a backup of your library. See the Apple Support article Back up and restore your iTunes Library.
There are a few ways to transfer your iTunes library from one computer to another:
When you get a new Mac, use Set-up Assistant (or Migration Assistant, if you’re switching from Windows) to move files—including your iTunes files—from your old computer to the new one. See the Apple Support article Back up and restore your iTunes Library.
Connect computers (over a wireless network or with a cable) and copy your iTunes files from one computer to the other.
Use iPod or a portable drive to transfer iTunes files.
Before you sell or give away a computer, don’t forget to deauthorise it (choose Account > Authorisations > Deauthorise this Computer). See Authorise a computer to play iTunes purchases.