Abstract: The ultrastructures of chloroplast in the mesophyll cells of five species of alpine plants grown on Daban Mountain(an altitude of 3900 m) in the northeast of Qinghai-Tibet Plateau were observed under TEM.The observations showed that there were a lot of starch grains in the chloroplasts of alpine plants,and the starch grains were usually round or oval in shape arranged along the longitudinal axis of chloroplasts.In the chloroplast of Polygonum viviparum,the central parts of the starch grains were heavy in electron-density,whereas the outer parts were light.In other four species,Gentiana przewalskii,Aconium tanguticum,Pedicularis kansuensis and Delphinium monanthum,the whole starch grains were light in.The abundant lipid droplets were also observed in the chloroplasts with swollen thylakoids in alpine plants.It was suggested that the variations of starch grains in the chloroplast of alpine plants as stated above were the result of the long-time stress under the ecological factors in Qinghai-Tibet Plateau,and were an adaptation to the environment.