Abstract: Abstract: The main vegetative constituents in roots of Glehnia littoralis during the late cultivation periods were mensurated. The results showed that: During the late cultivation periods of roots of Glehnia littoralis, the content of starch had significant difference, and the content of reducing sugar, that of protein and that of fat had extremely significant difference .The yields had extremely significant difference, too. According to every index being comprehensively analyzed, the mid-October should be the most suitable harvest period. Through peeled off and hot water, the content of reducing sugar was significantly declined in roots, which was only 0.8286 g/100g. Compared to the content of reducing sugar and that of protein in roots harvested in the same period, the content of reducing sugar and that of protein in roots being peeled off dropped 91.714% and 12.58% respectively. When the roots of Glehnia littoralis were used in medicine, they shouldn’t be peeled.