The planning and scheduling requirement of industry can not be satisfied by traditional scheduling systems. Companies need to put extra human resource to fix the result made by these systems. The main reason is an improper assumption of infinite capacity adopted by these scheduling systems. In order to improve the scheduling result, this research refers plastic injection industry¡¦s characters to implement a decision support system. The decision support system integrates Forward Finite Loading and Constraint Directed into our algorithm in order to minimize the increase in total cost, and raise the capacity balance between machines .According to the result of the practical research, we can prove this decision support system is more effective and efficiency than the traditional scheduling method.