> I want find the salt bridge interaction in my protein , can I use Avogadro for this work.
No, at the moment, salt bridges are not parsed by Avogadro's PDB code.
If you have a few example files it's something that could be added, but so far you're the first person who has asked about it. What would you like to see? Have you tried a specialized biomolecule tool like UCSF Chimera?