Several common crop straws,such as wheat straw,corn stalk and cotton straw,were treated by alkali,and analyzed by thermogravimetric analyzer(TGA).The calorific values of these crop straws were also measured,and their cellulose contents were determined by a nitric acid ethanol method.The results showed that,the calorific values of straw powder were in the order of cotton straw powder>wheat straw powder>corn stalk powder;the cellulose contents in wheat straw,corn stalk,and cotton straw were 37.91%,47.38%,and43.66%,respectively.Moreover,the cellulose contents in these straws increased after treated by 10% NaOH solution,and the increasing rates were in the order of wheat straw>corn stalk>cotton straw.This research provides a reference for the pretreatment and comprehensive utilization of crop straws.