I don't have place to hanging a punching bag, so I would like to know if it's good to place a punching bag leaning on the wall and punch it?
It isn't ideal. I don't think you're going to get much out of it, because part of punching bag training is reacting to the return swing. Additionally, some of your force will be transferred through the bag into the wall, which could possibly damage the wall if it's dry-wall. Also, the bag will probably not be the right height to punch without having to compromise your body structure.
You also won't be able to deliver round kicks with your shin, because your foot needs to clear the rear of the bag. I know you're only asking about punching, but just in case you want to kick, I thought I'd mention it.
There exist free-standing heavy bag stands, if it's the case that you just don't want to hang the bag from the ceiling. These are usually held in place with weights of the kind that you bench-press on the rear of the stand.
If you just want to punch something, and you aren't concerned with having a swinging target, you have two options:
- Buy a kick shield. Have a friend hold it, or find some way to strap it to a tree.
- Punch a tree. Just don't do it hard, and find a tree with smooth bark. You won't be able to work your techniques as intensely as with a punching bag, but it is an option. You may consider wearing hand-wraps for this purpose.
I would like to expand on The Wudang Kid's answer in that I found a stand on Amazon for about $100. Alternatively you could also pick up a BOB but those are significantly more expensive, around $270. Should you go the tree route as suggested above I would definitely suggest at minimum hand wraps and nomex gloves and definitely go lighter on the punches. Hope this helps, good luck in your training.
Knowledge source: Muay Thai figher, new jiujitsu practitioner, trained in Taekwondo, Boxing, and Muay Thai for over a decade.