The key of decision-making of manufacturing resource planning is material requirement planning (MRP). The traditional computing method of MRP is not efficient while the market is fluctuant and the customer demands are different. A new kind of optimized MRP model based on the real supply environment and the real demand is presented in this paper.The new optimized MRP model can improve the material demand plan effectively. Some aid information for decision-making such as price, ordering costs, holding costs, the working capital and restraint for safety stock are taken into account in the optimized MRP model. The discrete characteristics of the net requirements are considered in this new optimized MRP model, and this new model can make the decision-making of production process dynamically respond to the changes of real demand efficently.