Abstract: A design programming was presented for a high speed centrifugal air compressor supported with water lubricated bearings and driven by permanent magnet synchronous motor (PMSM). In order to satisfy the oil-free and high efficiency requirements of the fuel cell system, the compressor was designed structurally combining water lubricated bearing with PMSM. A dynamic optimization was first conducted on the compressor rotor, then the stability performances of different kinds of water lubricated sallow multi-pocket bearing were investigated. Finally, a prototype of the compressor was developed and tested. The results show that the air compressor prototype can proride compressed air with 350kg/h, aressure ratio at 6×10⁴ r/min. Steady operations at high rotating speed were obtained, and the feasibility of the design was verified.