## 1 Introduction  
With the continuous improvement of agricultural machinery intelligent design databases, most parts can be redesigned and put into production by means of reuse design. It is the core of intelligent design and advanced manufacturing technology of key parts of agricultural machinery to build a virtual prototype with advanced technology and complete functions for production simulation and data analysis [1, 2]. However, the current cost is too high for small and medium-sized agricultural machinery equipment enterprises to purchase large-scale intelligent design systems. In designing key parts of agricultural machinery that consist of numerous parts with high similarity, the calculation efficiency and the utilization rate of software function are low, and the coherence and flexibility are weak. Therefore, the construction of a virtual prototype and its unique knowledge base of key parts of agricultural machinery with strong functionality, high data abundance, low cost, and strong practicability is of great significance for the intelligent design of agricultural machinery to guide production [3, 4, 5]. In this work we analyze the existing intelligent design platform and research results. In terms of system functions, SolidWorks has released its commercial plug-in for collision detection. Users can select features and define the relative motion relationship between partsto obtain interference data. However, there is a lack of global data automatic detection and a real-time feedback function of multiple parts. [PERSON] designed the calculation method of fit clearance under various assembly conditions [6]; however, the computational efficiency of this method was low, and the algorithm process was cumbersome for the agricultural machinery assembly data with strong regularity. [PERSON] designed a multifunctional virtual prototype for product design data analysis [4,7,8][PERSON] [PERSON] constructed a simulation system to estimate production data [9, 10, 11], but they both lack the data compatibility of simulation analysis function and multiplatform interaction. In terms of data management, [PERSON] built a cross-system product data management platform [11]; [PERSON] built an algorithm for reuse data analysis and call [12,13]; [PERSON] designed the reconstruction algorithm of the feature surface to calculate the part feature data [14,15]; and [PERSON] used 2D sketches for reuse design and model retrieval [16,17]. However, there are still problems of poor real-time and simulation. In terms of interactivity, NX, Creo, and other mainstream commercial CAD software import parts and manually plan assembly through users during virtual assembly; [PERSON], used algorithms to construct assembly constraints to control part assembly [18, 19, 20, 21]; and [PERSON] combined virtual reality technology to develop a more interactive and practical design system [4,22, 23, 24]. In summary, the above research still contains the problems of low system function coherence, low simulation degree, poor interaction, high cost, low calculation efficiency, lack of dynamic update of data, and real-time analysis ability [25]. Based on the existing research, this paper further combines the features of key parts of agricultural machinery and advanced technologies, such as image processing and deep learning, to detect the feature parameters of parts and construct its virtual prototype and verifies the data accuracy of the virtual prototype by the method of the curvature radius of contour points. A special knowledge base containing enterprise production process data is constructed, a variety of design tests and data analyses are conducted using a virtual prototype, and the reliability of the knowledge base data is verified by comparing the theoretical value with the actual value. The virtual prototype and knowledge base are integrated in the virtual reality engine, and an intelligent design system for key parts of agricultural machinery is developed. Finally, a practical production case is used to indicate the practicality of the system.