Supply chain management is one of the main factors of successful organization. One of the important causes of its’ ineffectiveness is “Bullwhip Effect”. Most of previous studies were about its’ effect on one-product and two-echelon chains. In this paper, the authors try to study bullwhip effect on two and three-echelon chains which includes more than one product according to some assumptions. The main aim of the paper is to provide a measure for bullwhip effect that enables the analysis and reduction of this phenomenon in three-echelon supply chains with two products and determine its’ effective factors and reach to some ways to decrease bullwhip effect in these chains. To do this, Time Series; a suitable pattern for demand modeling in a two product supply chain; was utilized and Moving Average was used for lead-time demand forecasting. To prove that the expression for bullwhip effect measurement is true, the finding were compared by real information and results of simulation that in which, estimation error can be neglected. Finally, the finding showed that by reducing lead time and optimum selection of forecasting periods, the bullwhip effect can be reduced.