Poly (vinyl chloride) is more useable polymer than the others in the world. The industrial manufacturing of poly (vinyl chloride) (PVC) by suspension polymerization and other methods are carried out in batch reactors. In suspension polymerization with free radical mechanism, monomer, initiator and emulsifier are added to water. The productivity increase of these processes is directly related to the reduction of the time required to complete each batch. In order to reduce the polymerization time, the reaction would be carried out under an almost constant rate of polymerization. An attractive mode of operation is to run the process isothermally and to add a mixture of different initiators. An advantage of this technique is that the initiator mixture is added only at the beginning of the polymerization, which avoids the use of a continuous dosage system and its respective control. Using the optimal amounts of initiators in the reaction reduce the total processing time significantly, which reduce the operating costs and increase the efficiency. The objective of this study is to select the optimum formulation of mixture of different initiators which minimize the batch time consistent with constraint reactor heat transfer capacity. In the present work, a suitable mathematical model for the batch process of vinyl chloride suspension polymerization is studied and the suitable solver is used to solve it. By using this model and the appropriate algorithm, the optimum formulation of initiators is stated for reduce the total polymerization time.