Abstract: To explore the response of Bletilla striata to shading conditions,the two-year-old B. striata were cultivated under sunshade nets of 0%（as the control,CK）,50%,70% and 90% shading rate,the external morphology and leaf structure of B. striata were measured. The results showed that the plant height,leaf length,leaf width and leaf area were increased significantly under three shading treatments respectively,and the 50%shading treatment was the best. The stomatal density and wax particles in epidermis decreased gradually with the decrease of light intensity while the shape of chloroplast changed from nearly spherical to long fusiform.Moreover,the leaf thickness was increased,whereas the distance of adjacent vascular bundles was decreased under 50% shading treatment by the leaf cross-cutting observation. The less number of grana and thylakoid lamellae in chloroplast under CK treatment,and the more number of grana and the higher degree of thylakoid stacking in chloroplast under 50% treatment. However,there were the more stromal thylakoids and spacing between the lamellae under 70% and 90% shading treatment. These results suggested that the stomatal density,epidermis wax,mesophyll thickness,chloroplast shape,thylakoid lamellae and its thylakoid stacking might as the main structural basis factors of photosynthetic physiological response of B. striata to shading treatment.