Field experiments were conducted to investigate the effects of potassium levels（K2O 0,337.5,450,675,1 012.5 kg/hm2）on chlorophyll(a+b)content,photosynthetic characteristics of the Panax notoginseng leaves and storage root yield of twoyearold P.notoginseng.The results showed that application of potassium increased the content of chlorophyll(a+b)in notoginseng leaves,and improved the net photosynthetic rate(Pn),stomatal conductance(Gs)and transpiration rate(Tr).It also reduced the intercellular CO2 concentration(Ci),enhanced photosynthate production and accumulation,and increased storage root yield of Pnotoginseng.The highest storage root yields were all appeared in K3 treatments(675 kg/hm2)in different levels of K fertilizer.Compared with no potassium supplied one(K0),K3 treatments increased the yield of Pnotoginseng by 17.17%.The effects of potassium application on photosynthetic parameters were significantly different in different levels of K fertilizer.The content of chlorophyll(a+b)in notoginseng leaves,Pn,Gs and Tr had a trend experiencing increase to decrease,and the Ci had a trend experiencing decrease to increase with the increase of potassium application levels in the same growth period.During the whole growth period,storage root yield were all positively correlated with the Chl(a+b),Pn,Gs and Tr,but were all significantly negatively correlated with the Ci.Under the condition of this experiment,the highest economic yield occurred when the potassium application rate was K2O 675 kg/hm2.