The space-borne synchronous monitoring atmospheric corrector (SMAC) is a sensor that can obtain real-time spatial multispectral polarization information of the atmosphere. In this way, aerosol and water vapor parameters that are then used for the atmospheric correction of high-spatial-resolution images can be provided. A portable multichannel reference light source (PMRLS) was designed to evaluate the optical performance of the SMAC during environmental testing. The multichannel design of this source was consistent with that of the SMAC and had independent luminous components corresponding to each channel. A luminous element was equipped with a semitransparent diffuser plate, thus, enabling the luminous components to produce uniform illumination. To reduce the power consumption, a light-emitting diode and halogen tungsten lamp were chosen as the luminous elements at the visible and near-infrared band and the short-wave infrared band, respectively. The luminous element was driven by a low-noise stable current and cooled by an electric fan and cooling fin so as to improve the temperature stability of the PMRLS. In addition, the position of the PMRLS was limited by design to improve its repeatability. The radiance adjustment and performance testing for the PMRLS were performed using the SMAC. The maximal deviation in the radiance found during the PMRLS's radiance adjustment was within 7%, and the instability and non-repeatability values were less than 0.76% and 1.3%, respectively. Overall, therefore, the performance of the PMRLS meets the requirements for a quick evaluation of the SMAC.