In order to improve the design efficiency of rotary blade roller, a rapid design system was established for rotary blade roller based on knowledge engineering: On the basis of collecting the design process and the rules of the rotary blade roller, the knowledge libraries including the parameter library, rule library, and instance library have been established for the rotary blade roller, which were added, queried, and modified to the database by using SQL language. Appling a hybrid reasoning method based on RBR and CBR, a fast design platform for rotary blade roller with API secondary development tools and VB.NET language has been developed under the system development platforms of Solid Works and Visual Studio. Size-driven model changed and parameterized rapid design of the rotary blade roller have been achieved under different agricultural agronomy requirement. Under the Intel i5 processor and 8 GB system memory configuration environment, the rapid design system can be run for 3 to 5 minutes to design a CAD model of the rotary blade roller with output files under the user’s requirements, which meets the needs of application.