All parts of Datura plants contain dangerous levels of the tropane, alkaloids, atropine, hyoscyamine and scopolamine which are classified as deliriants, or anticholinerqics. The aerial parts of Datura stramonium were harvested in flowering stage from botanic  garden of Sistan and Baluchestan university in the mid, June 2012. The methanol extract was gathered by soxhlet apparatus and concentrated in rotary. We could generate total alkaloid solution by the use of sulfuric acid, ammonia and chloroform. The alkaloid total was purified by passing from a column of silica gel and was washed by a combination of ether petroleum and chloroform solutions. The existence of alkaloid and purity of the generated solution from the column by the thin-layer chromatography technique was confirmed. Then this solution was analyzed by GC-MS technique. The scopolamine alkaloid was identified with the amount of 5.77%. This combination is the reason of antioxidant feature of the plant extract.