Abstract: The framework system for the knowledge-based roll design system and the knowledge base for roll design are established by means of the KBE（knowledge-based engineering） process and the application of rele-vant knowledge relating to roll design and the experiences as achieved by the designers for a long time.As a re-sult,the knowledge-based system for design of roll of weld pipe mill is developed so as to enhance the intelligent level,the efficiency and quality of design of the roll,and lessen dependence of the design on the experiences of the designers.