First of all, we need to download the OS X 10.8 Cougar installation file, there are two ways:
One: from the Mac App Store, the current beta version is from the Mac App Store using the redemption code to redeem; the future release of the official version is still to download from the Mac App
Store. After downloading, please go to the application folder and find the app file "Install Mac OS X Mountain
Lion" (the current version has the suffix Preview 1)
The second is to download it through other network methods. Usually the download is a dmg (or other compressed format) file, which you unzip first, and then you should also get an "Install Mac OS X Mountain Lion" (with the Preview X suffix) for you to drag into the apps folder.
OS X Mountain Lion 10.8 beta download
Our goal is to find this file, the current version is this "Install Mac OS X Mountain Lion Preview 1"
After that Right-click on the file and select "Show Package Contents"
Open the Contents directory, then open the SharedSupport directory, and find the file "InstallESD.dmg"
Double-click this "InstallESD.dmg" file, it will be extracted to the desktop of a temporary image-like disk drive
Secondly, prepare a USB flash drive to start making.
It is currently recommended that the USB flash drive be at least 5GB in size. Or you can partition it from your removable hard disk.
We took an 8GB USB flash drive and made it:
Insert the USB flash drive, open Applications - Utilities - Disk Utility
Check the USB flash drive on the left side of the list, select the "Erase" tab on the right side, and then select "Mac OS X Extension (Logging)" underneath it, and you can name it whatever you want. You can name it whatever you want. Finally, select "Wipe"
OK, the name here is MacX, OK, now select MacX from the left list, and click "Recover" in the right upper tab
After that, you can find the new "Mac OS X Extension (Logged)" on your desktop in the left list. Mac OS X Install ESD", drag and drop the source and destination disks according to the pattern in the picture below:
Once you've placed it, you can tap Recover, and after the recovery is complete, your Cougar Installation USB flash drive is done.
When you turn on your computer, press and hold Option, and choose to boot from the installation USB flash drive named "Mac OS X", then you can install a new system on your computer
.