The evolution of retail formats is the basis for promoting the transformation and upgrading of the retail industry, and is also the endogenous power to achieve “structural adjustment and expansion of domestic demand”. This paper takes the retail format of fresh products as the research object, constructs an economic model from the perspective of supply and demand, theoretically deduces the evolution mechanism of the retail format of fresh products, and verifies it with the evolution practice of the retail format of fresh products in China.The research results show that: (1) the evolution of fresh retail format is a process of constant changes in the balance of supply and demand in the retail market, and the enterprise supply behavior and consumer choice behavior jointly determine the evolution of format; (2) Under the principle of maximization of consumer effect and enterprise profit, different retail formats usually present a coexistence relationship with a certain proportion of their own advantageous products; (3) Retail enterprises can attract consumers by reducing transaction costs, but they need to further reduce operating costs to expand the range of advantageous products and thus increase market share.