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 Setup 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 de-authorise it (choose Account > Authorisations > De-authorise This Computer). See Authorise a computer to play iTunes purchases.