Abstract: Using F15,F901,G15,Switzerland N4and GR911cassava varieties as materials,the dry matter content,protein content,starch content,soluble sugar content and yield in harvest time were determined during tuberous root of enlargement stage.The results showed that the dry matter and starch accumulation of tuberous root were positively correlation with growth period,which contents of testing varieties(except F901)were gradually increased with time prolonged.While the protein content were first rises then falls during the growing season,and the peak happened at November.According to the performance of starch and yield,the recommended harvest times of F15,F901,GR911were January,which starch content kept continuous rising trend.While the recommended harvest time of G15and Switzerland N4 were December,which starch content increased slowly or remained unchanged during December.