Ethanol fuel from biomass is conventionally produced via the hydrolysis of biomass catalyzed by acid. In this paper, it is understood that the degree of polymerization of cellulose is randomly distributed and that the rupture of beta-1,4-glucosidic bonds during acidic hydrolysis of cellulose is a process of continual depolymerization. From this perception, a model is established for the continual depolymerization of cellulose catalyzed by acid. Meanwhile, analog computation resulted in the activation energy and the reaction rate constant related to the rupture of beta-1,4-glucosidic bonds. The established model is highly validated by test runs and thus assumed as a model that can be used to describe the depolymerization route taken in acidic hydrolysis of ceflulose. The calculated activation energy and rate constant for the rupture of beta-1,4-glucosidic bonds correspond to the rule of acidic hydrolysis of cellulose. Investigation of the model is of great significance in further studies on the hydrolysis mechanism of cellulose.