1 Install the USB flash drive on a windows computer without virus and without Internet access. Steps:

1. 1 Download rufus software or cracked ultralISO software;

1.2 Download the official original windows system installation image file of Microsoft (the file is in ISO, WIM or ESD format, and you can get the download link of ed2k on the "msdn, I'll tell you" website);

1.3 Insert the USB flash drive (capacity requirements: generally, Win XP needs a capacity greater than 1G; Win7, Win8.x and Win 10 depend on the size of the system image file, and generally need a capacity greater than 4G or 8G);

1.4 In Disk Manager, set the main partition of the U disk (if it is not necessary to establish it first) as the active partition;

1.5 Start rufus or floppy disk, and write the system installation image file (ISO format) to the U disk (the U disk file system is FAT32) by "writing hard disk image"; If the target computer is a combination of UEFI and GPT, you need to set the UEFI option during this process;

2 On the computer where the system needs to be installed:

2. 1 Plug in the USB flash drive for bootable system installation;

2.2 There are two operation methods to choose from after startup:

A enter the UEFI/BIOS setting interface of the motherboard, set the USB flash drive as the first boot device, and then save and restart it (all motherboards can be used, and older motherboards can only use this method);

B in the motherboard boot menu, select boot from USB flash drive (applicable to most mainstream motherboards at present).

Note: (a) The buttons (or key combinations) for entering the UEFI/BIOS setup interface of the motherboard or starting the device selection menu vary with each motherboard, so you need to read the prompts on the screen carefully or consult the motherboard manual for confirmation. In addition, some keyboard keys need to be used with Fn or other keys. (b) If the target computer is started by UEFI, you need to select the UEFI startup item of the corresponding U disk;

2.3 Start installing the system, format the partition installation system when selecting the installation location, and then continue the installation according to the prompts.