In recent years, component-based software has been widely used in various application domains and becomes a fairly popular software form. However, due to the lack of information about the externally-developed components, system testers (i.e., component users) generally can't perform effective testing (especially regression testing) on their component-based systems. Component users don't know the details about change in component, so they aren't able to select the proper test cases to retest the modified system. In this paper, we present an improved regression testing method based on the enhanced change information of component version to test the software system containing some modified components. It is a collaborative testing method, needing the joint participations of component developer and user. Component developers calculate the change information from labeled method call graph and provide it to component users via XML files. Component users use this change information and their instrumentation records together to pick out test cases for next-round testing. In addition, we have employed preliminary experiments on some medium scale systems, the experiment results show that our regression testing method is fairly feasible and cost-effective in practice.