At present, the contradictory between the high speed process ability and the low speed I/O devices has become one of the main problems in multicomputers. So it is necessary to develop parallel file system of high performance. PFS is a parallel file system designed for a multicomputer, one of the 863-plans. Its goal is to decentralize the management of I/O devices into multiple process nodes so that files can be distributed into different physical devices controlled by different process nodes, and accessed as parallel as possible. This paper states the basic design, implementation methods and approximate performance analysis about PFS.