edit users of assigned domain i need to one role like 'domainAdmin' in a domain can edit only users of the assigned domain not another domains. is this possible with domain access itself or another modules?
A good start would be here: http://drupal.org/project/domain_roles - This allows you to segment roles by domain. So you could create different roles, then assign those roles to users and by way of other access modules (Content Access could be useful but I'm not certain how it handles user entities) you could then limit the users to only their domains.

FWIW, this used to be done in Drupal 6 by way of the unstable module: http://drupal.org/project/domain_user_edit - Could be worth contacting the maintainer and seeing what you can do to take it over for Drupal 7 and on.