Abstract: On the basis of newsvendor model and information revelation theorem,the manufacturer,retailer and e-intermediary profit models have been set up in online-reverse-auctioning a contract with options and side payment.Model optimization gives the optimum option order quantities under two e-commission systems.By comparing the optimum option order quantity with the optimal production capacity,the characteristics of supply chain coordination under different contract types and e-commission system is analyzed.The conclusion is drawn up as follows:on auction of the contract with options and side payment where product has a single-period stochastic demand,the system will not be coordinated if the manufacturer gives the side payment.If the retailer gives the side payment,system coordination is related to e-commission system.That the winning manufacturer pays the e-commission is beneficial to system coordination and profit allocation.

Key words: online reverse auction, supply chain coordination, contract with option and side payment, e-commission