Abstract: Application of interactive and intelligent virtual reality assembly technology is still at the starting stage in China, especially in the field of agricultural machinery design and manufacture.In order to complete intelligent virtual assembly of complex mechanical seed-metering device, and integrate innovation achievements plus professional knowledge of the 2B-JP-FX series mechanical seed-metering device with double cavity composite plate, shorten design and development cycle, the 2B-JP-FX series of mechanical seed-metering device with double cavity composite plate were studied, and the man-machine interactive virtual assembly system was proposed based on matter-element identification.The concept of assembly matter-element is proposed, which is defined as general designation of assembly levels which includes assembly reference elements, type of assembly constraints and assembly direction.All the assembly information of assembly basic element and part can be expressed completely and accurately by the information of assembly matter-element.To realize assemble matter-element information identified and extracted by the intelligent assembly system, the assembly intention captured and assembly matter-element information was encoded into semantic encoding.Encoding rules meet the characteristics of integrality, universality, characteristic, uniqueness, comprehensiveness, computability and cleanness.Then, corresponding assembly reference element should be built, and assembly matter-element encoding identified in the 3D model file, so that encoding can be extracted by program.To transform assembly information into assembly constraints, and intelligently guide automatic assembly, the intelligent assembly system based on assembly matter-element identification was designed, with Visual Basic acting as development language and CATIA software as secondary development tool, and assisted by man-machine interface.CATIA software was accessed out-of-process through VB, then the assembly matter-element identification of all components were extracted, and the rules of corresponding information extraction were formulated based on the rules of assembly the matter-element identification, thus assembly information could be extracted and integrated, and was converted to assembly constraints.To make the system function more modular and operation simple, and meet a wide range of user groups, organic combination of human cognitive and logical operations of computer, a human-computer interaction interface was set in intelligent virtual assembly system.Main function of the interface was selection of the assembly sequence and guide of assembly.Results of system test proved that the system has got anticipated results, with rapid and accurate assembly of seed-metering device 3D model.The general rules of matter-element identification assembly was obtained, which was the basis of effectiveness and feasibility of the intelligent virtual assembly system.The system can not only propose an advanced virtual simulation method for researching the 2B-JP-FX series seed-metering device, but also lay technological foundation for digital repository of seed-metering device.Meanwhile, it provides reference for intelligent virtual assembly of other complicated mechanical equipment.