The IBM SP1 is the first member of the IBM Scalable POWERparallel series, a distributed memory parallel computer based on RISC System/6000 processing element. In this paper, the benchmarking exercise of two message passing libraries, MPL and PVM, on the IBM SP1 for SPMD programming is described. We will discuss the benchmarks used in our experiment, and present the results we obtained. Our results indicate that to achieve performance improvement and to reduce the communication overhead, the use of the high performance switch is essential on the IBM SP1 machine.