PVM (Parallel Virtual Machine) software is one of the most popular software envi ronments used on parallel workstation cluster system. However, with the rapid in crease in the speed of local area networks as well as in the performance of work station, PVM, which is based on the low-efficiency internal and the low-effici ency communication protocol, has become the bottleneck of the cluster systems. I n this paper, it is explained how PVM restrains the performance of clusters, by pointing out and analyzing the limitation of PVM's mechanism. Then the details o f the design and implementation of HPVM (High-performance PVM) are given, which is based on a high-speed reduced communication layer named FMP (Fast Message P assing).