Abstract: The change pattern of major components and hydrolase in the cell wall of upper tobacco leaves with temperature and humidity during the bulk flue-curing process was studied by using the electric-heated flue-curing barn designed by Henan Agricultural University. The results showed that pectin methylesterase (PME), polygalacturonase (PG) and cellulase were highly active at 38 to 48 oC. Correlation between PME and cellulase was highly positive significant. During curing, leaf soluble pectin content increased continuously while protopectin, total pectin and cellulose contents decreased continuously. Correlation analysis showed that the relationship of pectin (total pectin, protopectin and soluble pectin) with PG was more closely than that with the PME.