In this article, Traditional Chinese medicine Ophiopogon japonicus was the study object, the precipitation process model of Ophiopogon japonicus polysaccharide based on BP neural network algorithm was established according to the measured data. The principle of BP neural network and the feature of selecting model parameters were introduced, and the improved BP algorithm was proposed. After analyzing the precipitation process of Ophiopogon japonicus polysaccharide, the model parameters of polysaccharide precipitation process were determinimaled, and then the neural network model was established. At the last, the simulation results were analyzed, the model meets control requirements.