The catalytic properties and thermodynamic kinetics of the endoglucanase from a marine Bacillus subtilis were analyzed. Optimum pH and temperature of the endoglucanase activity were 5.0 and 35 degrees C. The endoglucanase activity, melt point temperature was 1.13 folds (247.02 U . ml(-1)), 2.1 degrees C higher (392 degrees C) in 6% ethanol solution than that (218.60 U . ml(-1)), (37.1 degrees C) in free ethanol. At 40 degrees C-55 degrees C, Gibbs free energy, Delta G, and the content of alpha-helix was higher in 6% ethanol solution than that in ethanol free solution. The increasing of alpha-helix content led to higher activity and better thermostability in ethanol solution. The cold adapt ethanol tolerant endoglucanase was valuable for bioethanol product by simultaneous saccharification and fermentation process. (C) 2018 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.