A general structure of the network consists of one provider and two buyers, which is called a divergent structure. In the divergent structure, the allocation occurs because it is difficult to meet all of the buyers' demands, resulting in shortage games. Considering that the shortage game leads Bullwhip effect, reducing the shortage game will also reduce the Bullwhip effect. Previous studies suggest that information sharing will enhance the performance of the supply chain and reduce the Bullwhip effect, but adverse effects may occur depending on the type of information shared. This study researched what information should be shared to increase the performance of the supply chain and lower the negative effects such as Bullwhip effect. Opportunism information sharing model(A Model), Competitor information sharing model(B Model) and Supplier and Competitor information sharing model(C Model) were simulated by method of system dynamics, and each model was compared in terms of buyer inventory, customer service rate, and supply chain cost. As a result of the study, it was demonstrated that sharing the supplier's inventory and the other party's order volume can increase the performance of the supply chain by 16.3% and reduce negative effects such as Bullwhip effect.