Abstract: The photosynthetic characteristics of four cultivars of tung tree were measured with lico-6400 photosynthetic instrument.The results showed that:⑴ Net photosynthetic rate , stomatal conductance and transpiration rate of the cultivas‘Putaotong’,‘Xiaomitong’and ‘Duiniantong’were changed as single peak curve,while ‘Damitong’was changed as bimodal peak curve;(2) Intercellular CO2 of four cultivars of tung tree concentration appeared to vary in a V-shaped curve; (3)The order in daily chang of average net photosynthetic rate of them was taken as‘Putaotong’>‘Xiaomitong’>‘Duiniantong’>‘Damitong’; (4) The impact order that main ecological physiological of net photosynthetic value of tung tree was transpiration rate>intercellular CO2 concentration>PAR>stomatal conductance.