Producing ethanol from biomass is consisted of four main steps: biomass pretreatment, enzyme hydrolysis, fermentation and downstream processing. Bioethanol is an alternative way to reduce gasoline consumption and carbon dioxide emissions from vehicles. Cellulases which are divided into endoglucanase, cellobiohydrolases and beta-glucosidases, play a significant role in converting Lignocellulosic biomass into fermentable sugars.