Jagged Animation
 

I was using normal rigging on my character. But when I animated it, for example I animated the hand from point A to point B, the animation in between appear to be jagged, just like as if I've add noise into it, but actually I didn't. May I know how to solve this problem?

what exactly does it look like ?

It could be that you have motion blur activated,
with low antialiasing, that would be 5 figures on top of each other, making it look a bit jagged if you don't have a lot of movement.

Sorry, my explanation is not good, so maybe you don't get what my situation is.

My problem is not the render output looks jagged, but is the animation itself.

For example if I animated the hand move from front to back, it should be a smooth movement. But the hand movement ended up to be very shakey.

If you have a rendered animation you could show us that would infinitely helpful in diagnosing the problem.

If you're experiencing a stuttering, "jagged" motion in Layout itself [not an actual rendered animation, or preview], it might be that you're probelm is lag and not the actual motion itself. If you're just scrubbing the timeline or hitting "play" it could be that your PC isn't fast enough to keep up with the amount of polygons you're throwing at it.

Let us know if you're in Layout and or if the "jagged-ness" persits in the rendered animation as well. If you're problem is lag then there's a bunch of things that can be done to help that.