In the e-commerce environment, the composition of product supply chain is very different from the traditional supply chain, and the impact of product demand on supply chain operations has been an important research topic, and in which the most classical result is the bullwhip effect, however, this paper focuses on the product demand, study its effect to the various indexes in the process of supply chain operation.Use system dynamics simulation method to study the demand evolution phenomenon, and for different types of products, use agent simulation method to construct two types of product supply chain model in the e-commerce, and integration these two models together to form a simulation model which demand effects to the supply chain.Do simualtion experiments by Anylogic, investigate the impact of different parameters in the demand evolution model on the demands and also supply chain operations.