With the increasingly furious competition and the changes in the market environment，the choice and the adjustment of business models become more and more important for retailers．The retailer’s business model selection conditions，and the condition of transforming when market environment changes are studied．By comparing the retailer’s profit under the reseller model，the marketplace model，and the hybrid model，the condition of the retailer’s business models selection is given．When the market environment changes，the profits of the retailer when not changing the business model and when turning into hybrid model are compared，and the transformation mechanism of retailer’s business model is obtained．Finally，considering the development of China’s online retail industry，the main conclusions of this paper are verified．Our results suggest that the reseller model would be the equilibrium when the competition (complementarity) intensity，commission rates，and fixed costs are small; while the marketplace model will be the equilibrium when the competition (complementarity) intensity，fixed costs and commission rates are big．Interestingly，the hybrid model would also be the equilibrium if the competition ( complementarity) intensity，fixed costs，and commission rates are intermediate．Meanwhile，the equilibrium structure is also moderated by the indirect network externalities if the indirect network externalities are low，and the marketplace model will be the equilibrium model; while the indirect network externalities are high，the reseller model will be the equilibrium model; the hybrid model would also be the equilibrium if the indirect network externalities are intermediate． Finally，if the potential demand of the product changes to positive and commission rates are big ( small) ，the retailer taking the reseller model ( marketplace model) is more inclined to change to the hybrid model with the increase of the potential demand; if the potential demand of the product changes to negative and commission rates are small (big) ，the retailer will not change business model with the increase of the potential demand．