Abstract: The relationships between soluble sugar contents in the leaves and the starch accumulation in the root tubers of cassava were studied with 8 cassava varieties (SC205, SC201, SC5,GR891, FuXuan01, SC124, XinXuan 048 and XinXuan056)in this experiment. The results showed that the soluble sugar contents in the leaves increased from the root tuber setting stages to the ripping stage, and the soluble sugar contents in the leaves existed evident positive relativity to the starch accumulation in the root tubers. The reducing sugars content in leaf varied in the same trend. But the sucrose content in leaf reduced from the root tuber growth stages to the ripping stage. The sucrose contents in the leaves existed evident negative relativity to the starch accumulation in the root tubers. Eight cassava varieties had the same trend.