Plant performance,soil water gravity,distribution of plant roots in soil and three physiological parameters including conductivities of leaves,contents of MDA and SOD activities were tested under different water treatments for three cold-season grasses(Festuca arundinacea Schreb.,Freedom Ⅲ of Poa pratensis L.and Putter of Agrostis plustris Hunds.).We discussed the physiological and ecological mechanisms of drought stress for these grasses and compared differences in their drought tolerance.The best plant performance,with the lowest change in soil water gravity,strongest SOD activity and least damaged leaf cell membranes was Festuca arundinacea while Putter was the worst.