Taking one year plant of Codonopsis lanceolata as the material,the rule of yield accumulation of Codonopsis lanceolata were studied by the growth curve to decide the optimum harvest period.The results showed that the rule of yield accumulation of the root can be divided into six times,consumption period,slow growth period,rapid growth period,stagnant period,re-growth period and dormancy period,respectively.The best harvest time was early Octorber.