Abstract: The seasonal changes of photosynthesis and transpiration of both natural and planted one to three years Puccinellia tenuiflora,climate factors such as sun quantity,air temperature,earth temperature,relative humidity,rainfall and evaporation are measured.The relationships between seasonal changes of photosynthesis and transpiration of P.tenuiflora and the climate factors are analysed by correlation coefficient and path coefficient analysis.The earth temperature in the analysed climate factors directorly affects the seasonal changes of the photosynthesis and transpiration characters such as photosynthesis rate,transpiration rate and water use efficiency of P.tenuiflora most.

Key words: Puccinellia tenuiflora, photosynthesis and transpiration character, seasonal change, climate factors。