Abstract: In order to investigate the response of Peganum harmala L. to light and water, a two-factor controlled trial of light and water was conducted, in which two light gradients（full light T1 and shade T2） and three water treatment gradients of W1（1 d watering）, W2（7 d watering） and W3（14 d watering） were set by planting in a field, with each watering volume of 15 L·m^-2, to analyze the effects of different light and water. The effects of different light and water treatments on morphological indexes and biomass accumulation of P. harmala were analyzed.The results showed that the growth of P. harmala was better than that of the shading treatment under full light conditions, and the branch length, ground diameter, number of leaves and number of branches increased by 83.64%, 67.21%, 41.56% and 116.34%, and the aboveground and underground dry weights increased by 250.77% and 340.79%, respectively, in the T1W1 treatment compared with that in the T2W1 treatment. The growth of P. harmala was restricted, leaves were shed, and branching was reduced under shading and high water stress treatments, but there was no seedling death. This indicates that P. harmala shows light-loving characteristics in the seedling stage and has strong adaptive ability, which is recommended to be used as a material for landscaping and greening of barren mountains in areas with sufficient light.