In a reflective high concentration photovoltaic (RHCPV) system, density-uniformity of solar energy flux irradiates upon receiver surface can directly affect solar cell's photoelectric conversion efficiency. Uneven high intensity irradiation will also introduce "hot spots" which cause damages to GaAs solar cells. This paper presents a two-stage reflective mirror-type concentrator to achieve the uniformity of energy flux on receiver. A computation software, TRACEPRO, is used to model and numerically simulate the two-stage reflective mirror-type concentrator. Simulation results show that a flux uniformity of greater than 99.5% and effective area ratio for the photoelectric conversion of 77.0% can be achieved. The impacts of theoretical concentration ratio to the effective area for photoelectric conversion, maximum irradiance, average irradiance, and focal length are evaluated. At constant concentration ratio, the effective area for photoelectric conversion, the maximum irradiance, and the average irradiance are not affected by the focal length of PR. When the ratio of flux (light beams collected by the receiver) and emitted flux (incident light beams) is constant, the relationships of the maximum and average irradiance and the theoretical concentration ratio are linear, and the effective area for photoelectric conversion is also not affected by the theoretical concentration ratio. Meanwhile, a microchannel radiator is designed and studied, and GaAs solar cell surface temperature decrease with the increase of flow rate in microchannel.