Abstract:Objective To study the effects of N，P，and K fertilizers on the growth and accumulation ofsecondary metabolites，to reveal the accumulation relationship between the biomass and the secondary me-tabolites in medicinal plants in the plantation, and to establish the basic theory of fertilization in medicinalplant culture. Methods Orthogonal design was used to study the effects of nine combinations of N，P，and K on the biomass and active constituents in three levels of three factors. While plants flowered，theywere harvested，weighed，and smashed. Then contents of N，total caffee esters, and scutellarin wereanaylzed. Results High amount of N，P，and K fertilizers was optimum to the accumulation of biomass，but low amount of N，P，and K fertilizers was optimum to the accumulation of total caffee esters andscutellarin. The N fertilizer significantly increased the biomass and decreased the content of total caffee es-ters and scutellarin in Erigeron breviscapus，but did not affect the active constituents yield. The effect of Pon the accumulation of active constituents was higher than that of K，but its effect on the biomass accumu-lation was lower than that of K. The effect of K on the active constituents yield was the highest. Conclu-sion N，P，and K fertilizers could increase biomass and active constituents yield，nevertheless，decreasethe contents of flavonoids in medicinal plants.