Abstract: For the purpose of investigated the correlation of β-amylase activities and starch contents, the starch contents and β-amylase activities in the roots of different genotypes of sweetpotato during fruit-development stage were measured.The results showed that the starch contents of most genotype sweetpotatoes increased during the 28d period with the rate of 1% ⁵%.In the meantime, β-amylase activities of most sweetpotato strains decreased significantly.Correlation analysis indicated that the changes of the starch contents were related to the changes of β-amylase activities, but the plus-minus relativities and the significances varied among those different genotypes.