Using principle and method of the system dynamics, this paper takes a qualitative analysis on the inventory of supply chain of supermarket-oriented agricultural products, and compares with the supply chain of wholesale-oriented agricultural products. Two inventory models are established for these two different modes of supply chain. Through simulation of two models in the case of random demand and quantitative analysis of results, it is found that the inventory of supply chain of supermarket-oriented agricultural products has smaller fluctuation than that of wholesaler-oriented agricultural products. Besides, both the inventory level and bullwhip effect of above chain are lowered.