By introducing consumers' reference effect on dairy products' freshness in the study of a dual channel supply chain in dairy products with the involvement of a third party logistics service provider(TPLSP) and considering the freshness of dairy products is affected by the processing level of a manufacturer and the logistics service level of a TPLSP, this paper constructs the differential game models that are centralized, decentralized and under a contract of cost-sharing based on two-part tariff. Then the optimal equilibrium strategies of supply chain members in three cases are solved and compared. The results show that: when a certain condition is satisfied, the contract of cost-sharing based on two-part tariff can promote the processing level of the manufacturer, the logistics service level of the TPLSP and the overall revenue of the supply chain to the state under centralized decision-making, also achieve the perfect coordination of the supply chain by enhancing the revenues of the manufacturer, retailer and TPLSP; the dairy products' retail price in each channel is positively correlated with the market share of the channel and the price substitution coefficient; consumers' reference effect can encourage the manufacturer and TPLSP to increase their respective efforts and make increase in supply chain revenue.