Objective: To ascertain the best harvest time of radix cyathulae. Methods: Research the yield of radix cyathulae in different vegetal time by using experiments of the drying rate and mensuration on weight of individual plant. Mensurate the polysaccharides content of radix cyathulae amylase in individual plant through making use of spectrophotometry. Results and Conclusions: We confirm that the best harvest time of radix cyathulae is in autumn and winter when the plant has perished in November.