The bullwhip effect that occurs in supply chain leads to inefficiencies such as excessive inventory and back orders. This study investigates supply chain of a biomass. A simulation model using system dynamics approach is proposed to study behaviors and relationships within the supply chain and to determine variation of supply chain members demand related to end customer demand which has known as Bullwhip Effect. The purpose of this study is to represent the bullwhip effect in biomass supply chain by developing a system dynamics model and then presenting an improvement policy for preventing or decreasing bullwhip effect for supply chain members. We find that information sharing across the supply chain vanishes bullwhip effect for retailer and supplier also decreases this effect for distributor and manufacturer.