I am trying to develop a 3D RPG game by using java3D.
I want to ask is it only use java3D can do a RPG game?
What tools or other thing that i need to do in my development in order to come out a 3D RPG game.
Pls help me!!!
You can do the 3D part of 3D RPG using any of the many options that allow you to talk to the 3D hardware.
Please see my FAQ for a discussion of the various types of 3D libs availabel in Java.
But I have this sneaking suspicion this is your first game project. IF so you are way over-reaching and want to start learning on something much simpler.
My learning path was Java3D —> LWJGL (for openGL), and I think that is most natural way, to start with Java3D if you are new to 3D programming. When you master ( 
) Java3D and learn its downfalls, you will be ready to learn openGL language and gain control over number of things that were hidden from you in Java3D (but that didn’t bother you when you dont know very much…). So, my recommendation is : try to code some little project in Java3D, play with appearances, materials, lights, branch groups, and when you will need more, switch to openGL (via LWJGL library or JOGL, there are tutorials on that …)
Some year and a half ago I started doing a RPG in Java3D, just like you now (http://hvor.madpage.com/magicwoodsjava3d.htm) , but soon I switched to LWJGL (http://hvor.madpage.com/magicwoodslwjgl.htm). Based on that engine I even tried to do some FPS project (http://hvor.madpage.com/monstrumo.htm).
Good luck!