Abstract: This paper summarizes the study of the modeling and simulation of ethanol fermentation，and presents the characteristics of the models and the difficulty of simulation. The Monod equation could describe the competitive inhibitory actions well. The key problem of simulation is to optimize and solve the Monod equation. The Monod equation is converted into S system equations for optimization. The model here includes a mass transfer model. The difficulty of simulation is how to choose a proper overall transfer coefficient to simplify the solving process. And this simulation may perform the calculation of unstable equilibrium equations. Using cellulose as the substrate to produce ethanol is a new way to obtain ethanol at a low price. The mathematical model of the fermentation process should include the influences of polysaccharide decomposition and the inhibitory actions of the intermediate products. To simulate and optimize the ethanol fermentation process is helpful to decreasing ethanol production cost，and promoting commercial production. The direction of future study is to simulate the critical technique of cellulose fermentation and to compile application software，which is beneficial to optimization and automatic control.