I have read this. But it still didn't filled my brain yet.
When I play chess, sometime I often laughing and giving some pressure on my opponent.
Is it forbidden in Legal one? Are there a rule about it?
The FIDE Laws of Chess:
Distracting or annoying the opponent in any manner (other than making good moves!) is forbidden, and making noise is forbidden. So laughing in order to give pressure to your opponent is forbidden.