In order to enlarge the stable working range of a centrifugal compressor, the influence of inlet guide vanes with different angles on the performance of the centrifugal impeller of a micro turbojet engine was studied by means of numerical simulation. By comparing the internal flow conditions at different angles, it is shown that the inlet guide vanes at different angles has a significant influence on the impeller performance. Compared with the original design, the internal flow condition is improved under the condition of 20° guide vane, the surge margin and the maximum efficiency have been improved. It is proved that it is feasible to enlarge the stable working range of compressor by regulating the inlet guide vanes.