Abstract: To understand the effect of density on growth physiological characteristics of Platycodon grandiflorum , 5 density cultivation experiments were set, the shoot height, root length, root diameter, photosynthetic pigments contents, photosynthetic characteristics, absorption and distribution of nitrogen, phosphorus and potassium, contents of total effective components of different density treatments were investigated. The results showed that the density treatment had a significant effect on stem height, root length, root diameter, plant dry weight, contents of photosynthetic pigment, net photosynthetic rate, water transpiration rate, stomatal conductance, intercellular CO2 concentration and the total saponin content. Under high density, plant growth was relatively poor, the growth and physiological indexes decreased significantly, under low density, plant growth and development well, the growth and physiological index and the total saponin content was relatively high, but the biomass per unit area was low. The absorption trends of nitrogen and phosphorus inP. grandiflorum were same, the absorption increased gradually in early and middle development stage, and reached absorption peak at middle stage, later gradually reduced, mainly distributed in leaves and stems at early stage, had large proportion in fruit and flower at middle stage, later transferred to root, the density was To understand the effect of density on growth physiological characteristics of Platycodon grandiflorum , 5 density cultivation experiments were set, the shoot height, root length, root diameter, photosynthetic pigments contents, photosynthetic characteristics, absorption and distribution of nitrogen, phosphorus and potassium, contents of total effective components of different density treatments were investigated. The results showed that the density treatment had a significant effect on stem height, root length, root diameter, plant dry weight, contents of photosynthetic pigment, net photosynthetic rate, water transpiration rate, stomatal conductance, intercellular CO2 concentration and the total saponin content. Under high density, plant growth was relatively poor, the growth and physiological indexes decreased significantly, under low density, plant growth and development well, the growth and physiological index and the total saponin content was relatively high, but the biomass per unit area was low. The absorption trends of nitrogen and phosphorus in P. grandiflorum were same, the absorption increased gradually in early and middle development stage, and reached absorption peak at middle stage, later gradually reduced, mainly distributed in leaves and stems at early stage, had large proportion in fruit and flower at middle stage, later transferred to root, the density was inversely proportional to the amount of nitrogen and phosphorus absorption per plant. Compared with the absorption of nitrogen and phosphorus, the uptake of potassium by P. grandiflorum was less, and the distribution tendency of the three elements at early and late stage was similar, the distribution in every organ was balanced at middle stage, and the density had no significant influence on the absorption and distribution of potassium. Considering the biomass, the yield of medical part and the contents of effective components, in the north and central regions of Fujian, planting density ofP. grandiflorum should be about M3 (about 495 - 450 thousand plants/hm2).