Abstract: The full-feed harvesting method for grain combine harvester is not suitable for harvest of forage seeds．At the same time, due to different physical properties of legume forage seeds and gramineous forage seeds, existing self-propelled forage seed harvesting equipment in China is mainly used to harvest leguminous forage seeds．The harvest quality of gramineous forage seeds is average and loss rate is relatively high．Based on 9ZZ-2.4 self-propelled forage seed harvester, new type of gramineous forage seed harvesting device was discussed, which could be interchanged with legume collection platform．It had simple structure and convenient operation．Various technical parameters matched well with original harvester, and results were worthy of transformation and demonstration．