Hi everyone.,
Newby question: I bring maya obj file into houdini. Inside obj I have a lot of objects. When I apply rbd on it, it behaves like oneobject , but I want each individual peace behave separately. I applied group node to it, but defenetely miss something because it not working . Thanks for advance.

Try using an RBD Fractured or Glued object. These allow geometry with many different connected pieces to behave as such, rather than one single object.

thanks buddy., glue objects works amazing., i love the way it works in houdini