Rule-based reasoning (RBR) and weight decision making have been widely used in a lot of decision support systems. According to the waste phenomenon of manufacturing corporations due to the reasonless use of tools during production process, and considering the characteristics of former tool selection systems, develop a tool optimal selection system with Visual Basic 6.0 as development tool and SQL Server 2000 as database developing platform. The system adopts the rule-based reasoning and weight decision-making theory, combines fuzzy theory, artificial intelligent technology and production conditions of corporations. According to the information of workpiece and processing conditions imported by users, the system can select the reasonable tools for users. The system overcomes the limitation of single theory tool selection system, simplifies reasoning mechanism and structure of knowledge base, makes programmer easy to realize, promotes operation efficiency of system, and raises the accuracy and efficiency of tool selection in actual production. A developed prototype system and an example have verified some presented techniques and the research results are the basis of the future development.