In order to solve the problems in the turbo blade investment casting die design process，such as long design time，lower utilization of expert experience and lower level of intelligence，the knowledge engineering is introduced in the turbo blade investment casting die design，and an intelligent knowledge—based investment casting die design system is developed and the key technologies of the system are researched．The practical application results indicate that this system can reuse the expert experience efficiently and improve the efficiency and quality of die design．