Taking the biennial white flower P.grandiflorum and purple flower P.grandiflorum that from Jilin as the materials，their variance of genetic parameters of main quantitative trait and the correlation between different characters were studied.The results showed that in the flowering period and the fruiting period，the biennial purple flower P.grandiflorum root weight，the number of branch and the number of flowering had larger variation coefficient，all above 25%；their root weight and main root thick had significantly positively associated with the number of flowering.The biennial white flower P.grandiflorum root weight，branch number，main root length and the number of flowering had larger variation coefficient，all over 25%;their stem diameter，the number of branch had significantly positive associated with the root weight.Therefore，purple flower P.grandiflorum breeding could through the selection of number of flowering choose root weight，also could choose root weight for the breeding of high yield type.White flower P.grandiflorum breeding could through the branch number choose root weight.