You are taxing your machine resources too much. Try lowering your screen resolution, especially if you do not have a graphics card to help with the processing load. Without knowing what your equipment is, that is all I can say.

hmmm, could be my integrated graphics card causes this problem, but It only happens with deepin distro. I tried other distro, and it works fine. :-D

Usually, unless you manually set the resolution, the OS queries the system and makes a reasonable guess what it should use. An OS intended for older hardware, like Puppy or antiX, will guess low. An OS that prides itself on appearance will guess higher. The minimum system for deepin is a P4 with 1GB RAM (old). The target system, then, would be a dual-core with 2 GB and a graphics card (mature), and an ideal system would be a quad with 4GB or more and a 3D card (recent). deepin likes to look good. Your integrated graphics is fine.

Edited by rakan at 2015-12-6 13:59

Here is my computer specification ...
and thank you so much for the replying... :-)

Thanks for the specs. It's a good, solid machine and probably has a decent graphics controller that "borrows" CPU capacity and RAM if it needs it. Open the Control Center and click on Display to drop the resolution a little and try that. Keep dropping it a little more until the computer runs cooler and doesn't freeze or stagger. When all is well, you might try one resolution higher, but no more. If it plays video full screen, apps like LibreOffice should be no problem.