Abstract: Considering the characteristics of consumer time sensitivity differences, a Stackelberg game model was constructed for two scenarios: retailers only selling on the spot(not cooperating with the platform)and retailers simultaneously selling on the spot(cooperating with the platform). The optimal pricing and ordering strategies of retailers for spot products under different scenarios were analyzed. For the scenario of simultaneous selling on the spot, the drainage effect brought by self pickup of pre-sale stores was introduced, and the optimal discount coefficient, optimal pre-sale cycle, and optimal commission of group leaders for community group buying platforms were given. Research has found that after retailers cooperate with community group buying platforms, the optimal pricing of spot products increases, and the upper limit of consumer time sensitivity to spot products decreases; Only when the pre-sale traffic rate and consumer expectations for pre-sale products are high, can retailers and platforms have the possibility of cooperation. After cooperation, the demand for spot products decreases, which helps to reduce the ordering risk of physical retailers and lower inventory costs.

Key words: community group buying, Stackelberg game, pre-sale cycle