Abstract: The bullwhip effect,a popular phenomenon in enterprise's business,has a very large impact on an enterp ri se.This paper considers a simple two-stage supply chain consisting of a single retailer and a single vendor.First,we build inventory and mixed decision(inventory and pricing decision) models for the retailer on the delayed demand information.Then we analyse the impact of decisions on the bullwhip effect.The result shows that we can get the expectation of both prancing and order-up-to which have nothing as the delayed period based on retail optimal policy,and the retailer's inventory policy can produce the bullwhip effect which will decrease as the delayed period increases when delayed demand information exfists,but whether its mixed policy can produce the bullwhip effect according to the demand self correlation parameter,not the delayed period,however,it will decrease as the delayed period increases.Morever, comparing to an inventory decision,the retailer's mixed decision will make the bullwhip effect change intensively as demand is less correlated,otherwise change weakly.Therefore,for a retailer,appropriate delayed demand information and pricing flexibility can reduce the bullwhip effect.

Key words: bullwhip effect, supply chain, pricing policy, inventory policy, delayed information