Abstract: In this study, through the determination N, P, K content of in the different parts of annual Platycodon grandiflorus in the different growth period, analysis of demand conditions of various nutrients in different growth periods. Results showed that, N content in stem and leaves of Platycodon grandiflorus decreased gradually with the growth of plant, the content of N throughout the growing period were reduced 17.6% and 23%. N content in roots increased during the whole growth period, the growth rate was 33.7%. The content of P elements in various organs of Platycodon grandiflorus was different in each growth period. Among them, the P element content in roots was a maximum of 0.41% at the seedling stage, in the blossom period for a minimum of 0.34%, in the seed stage it was increased to 0.38%. The K content in roots has been increasing, the whole growth period increased by 0.24% . The lowest K content of stem and leaf in the squaring stage, respectively 0.42% and 0.51%. Experiments showed that, N, P, K elements was demanded strong in seedling stage and blossom stage.