From the perspective of virtual simulation teaching, this study takes the modern farm as the object of reference and designs the simulative teaching system of "Agricultural Mechanics" based on the Unity3D engine in order to improve the situation that it is difficult for teachers to teach and for students to learn the agricultural machinery in a traditional way. This study demonstrates some of the original developing thoughts, function and structure of the system, and introduces the key technologies involved in the development process. The application result shows that the system realizes the virtual visualization of agricultural machinery equipment in the process of production operation in virtual farms, and displays online the virtual dismounting and assembly, maintenance and operating principle of all kinds of farm equipment. It has certain practicability and teaching value.