An illuminance configuring illumination system for performing light adjustment in accordance with a determined illuminance range includes: at least one light assembly; a control module, provided with a set of preset light distribution curve data; a distance measuring module, configured to correspondingly measure a light distance of the light assembly, thereby obtaining a light adjustment reference information; and an illuminance measuring module, configured to detect the illuminance environmental variation in the surrounding of the light assembly, thereby obtaining a compensation reference information. The control module performs illuminance adjustment on the light assembly by referring to the set of preset illuminance range according to the light adjustment reference information and the compensation reference information.