An effective, simple, and convenient method to improve yeast's multiple-stress tolerance, and ethanol production was developed. After an ethanologenic Saccharomyces cerevisiae strain SC521 was treated by nine cycles of freeze-thaw, a mutant FT9-11 strain with higher multiple-stress tolerance was isolated, whose viabilities under acetic acid, ethanol, freeze-thaw, H2O2, and heat-shock stresses were, respectively, 23-, 26-, 10- and 7-fold more than the parent strain at an initial value 2 x 10(7) c.f.u. per ml. Ethanol production of FT9-11 was similar (91.5 g ethanol 1(-1)) to SC521 at 30 degrees C with 200 g glucose 1(-1), and was better than the parent strain at 37 degrees C (72.5 g ethanol 1(-1)), with 300 (111 g ethanol 1(-1)) or with 400 (85 g ethanol 1(-1)) g glucose 1(-1).