SOD, MDA and the content of soluble sugar and proline in Arabidopsis mutant plant sdg26 and wild-type plant Col under drought condition were investigated. The results showed that SOD, MDA, the content of soluble sugar and proline increased with increasing period of drought stress (5, 8, 11, 14, 17, 20 d), the increases were significantly greater in mutant plant sdg26 than those in wild type plant Col. In addition, water in leaves of wild-type plant Col gradually evaporated until death but mutant plant sdg26 still grew well after 20 days of drought stress. These results suggested that mutant plant sdg26 enhanced drought tolerance because of the loss of SDG26 gene function, which also indicated that histone methylation played an important role in drought stress tolerance in plants. .