Abstract:The accumulation of chemical constituents of Huai yam in different growth period were studied，which provided a theoretical basis for the scientific consumption，rational harvesting and standardized cultivation of Huai yam.The main varieties of Huai yam were Huai yam （variety）and Tiegun yam.The two varieties of Huai yam were collected at different growth period.The drying rate and the extract of Huai yam were measured.The content of Huai yam polysaccharide was determined by phenol-concentrated sulfuric acid method.The content of allantoin，adenosine，monosaccharide and oligosaccharide in the chemical constituents of yam was determined by high performance liquid chromatography.The results showed that the drying rate of Huai yam（variety）showed an upward trend from，and then stabilized.And the drying rate decreased to the end of february of the following year.The drying rate of Tiegun yam showed an upward trend from september to midnovember.After that，it tent to be stable.The chemical composition of the Huai yam was on the rise，and the content of the chemical components was fluctuated before december，and then stabilized.Huai yam（variety）is suitable for harvesting in mid-december.Combined with the factors of origin，it can be harvested after winter，but it is recommended to harvest before March of the following year to avoid the decrease of yield and active ingredient content.The Tiegun yam is suitable for harvesting in mid-december that year.