As to the luminance environment of the museums, the day-lighting design in their exhibition spaces has been analyzed, the typical museum design factors, such as day-lighting form, and layout of displayed items have been concerned and investigated by field trips. Then, the exhibition spaces are classified into different categories whose natural day-lighting environments are simulated by the requirements of displayed items. Under varied day-lighting conditions, the daylight parameters, i.e. day-lighting factor, day-lighting uniformity, luminance distribution and discomfort glare index (DGI) are evaluated. Therefore, the favorable day-lighting form and members in the corresponding exhibition spaces will be determined. the optimization strategies which optimize the parameters of varied day-lighting forms and members are proposed. It is concluded that the day-lighting quality would be ameliorated by the implement of optimization strategies, and favorable luminance environment in the different exhibition spaces of a museum are achieved.