Abstract: The dynamic features of yield and the contents of polysaccharides and total saponins in Codonopsis tangshen Oliv.roots were studied.The results indicated that the yield were higher among August,September and October.There were significant difference between two-year-old and three-year-old C.tangshen(p<0.01),while the content of polysaccharides did not(p>0.05).The polysaccharides content of two-year-old and three-year-old C.tangshen was higher at July,August and September.The total saponins contents of two-year-old C.tangshen was highest at November(1.11%),and lowest at September(0.77%).As for three-year-old C.tangshen,the total saponins contents was highest at June((1.07%)),and lowest at July(0.72%),no significant difference among August,September and October(p>0.05).The results suggested that the best harvesting time for C.tangshen was in August and September on the third year.