Abstract: To investigate whether proportion allocation based on past sales, compared with the fixed allocation, can improve the performance of a supply chain, a two-stage game modelwas set up to a supply chainwith one supplier andmultiple retailers, and the effects of the proportion allocation based on past sales on the performance were discussed. In addition, the fixed allocation and the proportion allocationwere researched comparatively. The results show that the proportion allocationwillmake the retailers ordermore than they need to increase the supplier s profits at the expense of the retailers profits, so it can improve the performance ofoverall supply chain only under some conditions.