Konjac glucomannan (KGM) were modified by deacetylation with sodium hydroxide, calcium hydroxide, sodium carbonate, sodium phosphate, respectively and mechanical properties of modified KGM films were investigated. The modification mechanism was explored by FTIR. Results show that deacetylation of KGM play an important role on the flexibility of the modified membranes, and the flexibilities vary with different modifiers. The flexibility of the films modified by sodium hydroxide is significantly higher than that of the others. The modified films with good flexibility were prepared by simple steps as follows: NaOH modifiers and KGM (1%) were added to water, stirred until the pH arrived at 9. And then the KGM swelled at the temperature of 50°C for 2 hours, the modified KGM sol was cast onto glass plates, the modified membranes were formed after dried at 50°C.