In CSCW community, group awareness model and application are an important research field. Base on the foundation of the past research, this paper proposes a model that support hierarchical role based structure called RHAM (role based hierarchical group awareness model) to analyze awareness information, base on relevant of tasks, as well as relationship of organization structure between collaborators. In RHAM, a group cooperation environment (GCE) is constructed firstly, and then GCE is extended by group awareness content, awareness hierarchy, the task decomposition rules. The model divides the awareness information into four levels based on role-task decomposition graph and relationship of group structure. Finally, the implementation mechanism, application and some related questions in the future research are discussed.