[Objective] To study the effects of K fertilizer on the biomass,yield and quality of Notopterygium forbesii de Boiss.,so as to provide scientific references for the reasonable fertilization.[Method] K fertilizer application test was carried in Duoba town of Xining by means of single factor and six levels randomized block design in the test,six application levels were set as 0,37.5,75.0,112.5,150.0 and 187.5 kg/hm2 respectively.[Result] K fertilizer had no significant impact on the plant height and number of compound leaves of Notopterygium forbesii de Boiss.;however the diameter of rhizome,the number of lateral roots,the dry weight of aboveground part,the root length,maximum leaf length,maximum leaf width and the dry weight of roots were improved by K fertilizer;the number of lateral roots was the largest when the application amount of K fertilizer was 75.0 kg/hm2;the diameter of roots and stem as well as the dry weight of the aboveground part were significantly promoted by 112.5 kg/hm2 K fertilizer;with the increase of K fertilizer,the number of roots,the content of volatile oil and alcohol extract in Notopterygium forbesii de Boiss.all improved gradually,which reached the maximum level under 150.0 kg/hm2 K fertilizer;with the applying amount of 150 kg/hm2,K fertilizer played remarkable role in improving the root length,maximum leaf length,maximum leaf width,dry weight of root,root yield,content of volatile oil and content of alcohol extract of Notopterygium forbesii de Boiss..[Conclusion] Taking into account the production costs,112.5 kg/hm2 K fertilizer was the best for the cultivation of Notopterygium forbesii de Boiss.. [Objective] To study the effects of K fertilizer on the biomass, yield and quality of Notopterygium forbesii de Boiss., So as to provide scientific references for the reasonable fertilization. [Method] K fertilizer application test was carried in Duoba town of Xining by means of single factor and six levels of randomized block design in the test, six application levels were set as 0, 37.5, 75.0, 112.5, 150.0 and 187.5 kg / hm2 respectively. [Result] K fertilizer had no significant impact on the plant height and number of compound leaves of Notopterygium forbesii de Boiss.; however the diameter of rhizome, the number of lateral roots, the dry weight of aboveground part, the root length, maximum leaf length, maximum leaf width and the dry weight of roots were improved by K fertilizer; the number of lateral roots was the largest when the application amount of K fertilizer was 75.0 kg / hm2; the diameter of roots and stem as well as the dry weight of the aboveground parts were significantly promoted by 112.5 kg / hm 2 K fertilizer; with the increase of K fertilizer, the number of roots, the content of volatile oil and alcohol extract in Notopterygium forbesii de Boiss.all improved gradually, which reached the maximum level under 150.0 kg / hm2 K fertilizer; with the application Amount of 150 kg / hm2, K fertilizer played remarkable role in improving the root length, maximum leaf length, maximum leaf width, dry weight of root, root yield, content of volatile oil and content of alcohol extract of Notopterygium forbesii de Boiss .. Taking into account the production costs, 112.5 kg / hm2 K fertilizer was the best for the cultivation of Notopterygium forbesii de Boiss.