[Objective] To study the effect of water stress on the structure and chlorophyll content of Sedum tatarinowii Maxim leaves,so as to provide references for its wide application.[Method] Wild S.tatarinowii sampled from Qiliyu National Forestry Park in Huoshan of Shanxi Province were cultivated and then treated by water stress.Four treatments were set up with the absolute water content in soil of 17.50%,13.60%,9.60% and 6.20% respectively,among which 17.50% was the control.The absolute water content of soil was determined by dry weighting method;while the chlorophyll content in the leaves was detected by acetone extraction method;the well-grown and clean leaves were sampled to prepare paraffin section and epidermis section so as to observe the type and distribution features of stomatal apparatus as well as the stomatal density.[Result] Under normal conditions,the leaves of S.tatarinowii were coated with wax on the surface,and had developed water storage tissue and idioblast with high water absorption capacity inside;the stomata closed during the daytime,while opened at night,the stomatal apparatus subsided;under water stress,the immature stomata appeared on the upper epidermis,and the density of mature stomata showed declining tendency,while the change of stomatal density on the lower epidermis was not obvious.The reaction of chlorophyll a and b to active oxygen was not significantly different,and the content of chlorophyll increased under certain degree of drought conditions;when the absolute water content in soil was 9.60%,S.tatarinowii could maintain its normal photosynthesis;while when the absolute water content in soil decreased to 6.20%,the chlorophyll content declined.[Conclusion] S.tatarinowii had typical features of xerophyte,when the absolute water content in soil maintained at a low level,the chlorophyll content remained unchanged or stable increasing trend,and the normal photosynthesis of plants could be maintained. [Objective] To study the effect of water stress on the structure and chlorophyll content of Sedum tatarinowii Maxim leaves, so as to provide references for its wide application. [Method] Wild S. tatarinowii sampled from Qiliyu National Forestry Park in Huoshan of Shanxi Province were cultivated and then treated by water stress. Flow treatments were set up with the absolute water content in soil of 17.50%, 13.60%, 9.60% and 6.20% respectively, among 17.50% was the control. determined by dry weighting method; while the chlorophyll content in the leaves was detected by acetone extraction method; the well-grown and clean leaves were sampled to prepare paraffin section and epidermis section so as to observe the type and distribution features of stomatal apparatus as well as the stomatal density. [Result] Under normal conditions, the leaves of S. tatarinowii were coated with wax on the surface, and had developed water storage tissue and idioblast with high wate r absorption capacity inside; the stomata closed during the daytime, while opened at night, the stomatal apparatus subsided; under water stress, the immature stomata was on the upper epidermis, and the density of mature stomata showed declining tendency, while the change of stomatal density on the lower epidermis was not obvious. The reaction of chlorophyll a and b to active oxygen was not significant different, and the content of chlorophyll increased under certain degree of drought conditions; when the absolute water content in soil was 9.60%, S. tatarinowii could maintain its normal photosynthesis; while when the absolute water content in soil decreased to 6.20%, the chlorophyll content declined. [Conclusion] S. tatarinowii had typical features of xerophyte, when the absolute water content in soil maintained at a low level, the chlorophyll content remained unchanged or stable increasing trend, and the normal photosynthesis of plants could be maintained.