Micro gas turbine is the core device of micro distributed energy system, and the vaned diffuser has significant influence on the compressor performance of micro gas turbine. The diffuser of a kW-class micro gas turbine was designed, and the numerical simulation was made on the micro compressor with vaned diffuser, especially the influence of vane incidence on the compressor performance. The results show that the pressure ratio and efficiency of compressor are very high in the case of large negative incidence at small flow rate, while the parameters drop quickly at large flow-rate condition with steep characteristic curve and narrowed working range. When the absolute value of diffuser incidence is relative small, the compressor shows a relative flat characteristic curve and wide working range. The slight variation of incidence contributes less to the performance of compressor. The static recovery coefficient is higher under positive incidence condition, and it becomes lower as the incidence decreases. The optimum incidence of vaned diffuser is not fixed and should be determined according to the specific working condition and the requirements for higher combustion efficiency.