Abstract: A micro centrifugal compressor was designed for centimeter-scale micro turbomachinery,which has a diameter of 26 mm,designed rotate speed of 240 000 r/min,and designed mass flow rate of 30 g/s.Three-dimensional numerical simulations under adiabatic and isothermal conditions of solid wall were performed by using the commercial CFD(computational fluid dynamics) software CFX.The results show that,as compared with adiabatic condition,the mass flow rate at the isothermal condition decreases 7.53%,total to total isentropic efficiency decreases about 18.1%,total pressure rate decreases 21.7% at the same shaft work input.Taking the effect of heat transfer into account,the micro centrifugal-flow compressor was redesigned.CFX simulation results show that the improved design satisfies the design requirement of the micro turbomachinery.