Two parallel programming models of shared-memory and message-passing are widely adopted. The programmability of message-passing is poor, while that of shared-memory is good. The OpenMP Application Programming Interface is an emerging standard for shared-memory. OpenMP on cluster supplies an OpenMP computing environment on cluster of workstations or PCs, which combines the friendly programmability of shared-memory with the fine scalability of cluster. Taking 7 well-known parallel applications on a cluster of PCs, this paper compares the performance of OpenMP/JIAJIA, an OpenMP system on cluster, with that of MPI, a typical message passing system. Experimental results show that the performance of OpenMP is averagely equal to 81% of MPI for the 7 applications running on 8-nodes, but the former is easier to use than the latter.