Objective To study the requirement of exogenous phosphorus for 2-year-old and 3-year-old ginseng seedings.Methods Two-and three-year-old ginsengs were used as experimental materials.Calcium superphosphate and phosphorus-free Hoagland solution were used as fertilizer,and the concentrations of P2O5 were set to be 0 mmol·L-1,0.5 mmol·L-1,1.5 mmol·L-1,3 mmol·L-1,6 mmol·L-1,8 mmol·L-1,respectively.The effects of different concentrations of phosphorus fertilizer on agronomic indexes,photosynthetic characteristics and accumulation of ginsenosides Rg1,Rb1 and Re were studied.Results The plant height,stem diameter,root weight,leaf area,relative content of chlorophyll,net photosynthetic rate and total saponins content of different year-old panax ginseng were significantly increased by applying phosphorus at 1.5-3.0 mmol·L-1.Among them,compared with the phosphorus-free group,the root weight of second-year ginseng was increased by 16％and the saponin content was increased by 24％;the root weight of third-year ginseng was increased by 89％and the saponin content was increased by 132％.The appropriate application rate of phosphorus fertilizer(phosphorus pentoxide)during the growth of second and third year ginseng was 26.6 mg and 53.3 mg of plant,respectively.Conclusion External application of suitable concentration of phosphorus fertilizer can enhance the external morphological characteristics of ginseng,improve photosynthetic physiological properties and increase the content of active ingredients.