To examine the effects of temperature elevation on physiological and chemical characteristics of three species in alpine meadow on Qinghai-Tibetan plateau,we conducted a simulation study in situ with open top chambers (OTC) followed the method of International Tundra Experiment (ITEX) from November 2002 to September 2007,and these OTCs were designed 5 kinds of size with bottom diameters of 0.85,1.15,1.45,1.75 and 2.05 m so as to rise different air temperatures.(1)The air temperature inside OTCs increased by 2.68 ℃,1.57 ℃,1.20 ℃,1.07 ℃ and 0.69 ℃ with increase of OTC diameter compared with ambient air.Accordingly,the soil temperature was also increase by 1.74 ℃,1.06 ℃,0.80 ℃,0.60 ℃,0.30 ℃,compared with Control.(2)We found that the elevated temperature had significant and complicated effects on physiological-biochemical characteristics of three plant species,and these indexes varied between different species.(3)Their response to experimental warming was not exactly the same way.These results indicated that if the air temperature increased within the range of 0.69 ℃ and 1.07 ℃ in the future,it may have positive effects on the physiological-biochemical characteristics of plants,and thus the environment would be more adaptive for plants living in.