A cooperative-server-group-based volunteer computing environment called P2HP is presented in this paper. All the nodes in P2HP are assigned as a certain role, named monitor, dispatcher, worker, DataPool and thus form a scalable layered topology for P2HP. P2HP is open, ease of use, scalable, fault tolerant and platform independent. A convenient API (application programming interface) set is also provided to support the development of parallel applications running on P2HP. The results obtained from performance analysis show that P2HP is a feasible approach for parallel processing.