Firstly, download the iso file of win7 system to the local hard disk;

Prepare an empty DVD and CD, and then burn Win 7 (the file format of iOS) to your CD.

Backing up important files in the old system with larger U disk and mobile hard disk; (If formatting is complete, this step is ignored. )

Put the burned win7 system disk into the CD-ROM drive that needs to reinstall the operating system, and start the computer;

Press del key to enter BIOS to set CD-ROM startup when booting, or press F 12 key to directly select CD-ROM startup when booting;

The Windows 7 installation interface appears. First, select Chinese (Simplified), Chinese (Simplified, China) and Chinese (Simplified)-American keyboard. Click Next after selecting it, and then click Install Now.

The installation agreement will appear when the installation program starts, so check the acceptance license terms;

Continue to the next step until the partition interface appears. Here, select the type of the first partition as system, and then click Next (the first partition that can be formatted before this is in the drive option (advanced) (a))；);

Wait for a while after the partition is completed, then remind the installer to start the service, and then remind you to restart your computer to continue the installation process, fully automatic;

After restarting again, take out the installation CD, and it will automatically detect that it is booted into the system with a hard disk. At this point, the Windows screen appears, and the installer is checking the video performance. Then, when you see the computer name, enter the PC name here (take any name). Click Next, the password interface will be skipped, and then the screen will go to enter the key. If it is genuine, fill it in. If not, don't fill it out. Just use the activation tool later.