Abstract:The influence of light intensity on the growth of Hymenocallis littoralis (Jacq.) Salisb. was studied in microcosm scale constructed wetlands with soil and gravel substrates. Four average light intensity（μmol m-2 s-1）treatments were used: 701 (full illumination, light I), 495 (71.4% of full illumination, light Ⅱ), 304 (44.7% of full illumination, light Ⅲ), and 141 (20.2% of full illumination, light Ⅳ). Results showed that plant height, leaf biomass, leaf length, and chlorophyll content were generally higher in the low light intensities (III, IV) than in the high light intensities (I, II). Total biomass per plant was higher in low light, but the difference is generally not significant. Photosynthesis and root biomass were greater in full illumination although the difference was not significant. Our findings indicated that H. littoralis had shading tolerance, and about 50% of sunlight is favorable to its growth. Effects of light intensity on growth varied with substrate type. Under the same light intensity, plants grew significantly fast in gravel bed than in soil bed. This plant may be used in constructed treatment wetland, specially as a lower-stratum plant in the mixed-cultivated wetlands from its height of about 100 cm, comparatively slow growth rate, adaptation to the gravel substrate, and favorable growth in suitable shading.