The invention provides an automatic bagging device for grains and relates to an automatic bagging device. The device comprises a grain bin and weighing system, a bag taking and bagging mechanism, an automatic grain bin opening and closing mechanism, a bag opening auxiliary device, an automatic transmission mechanism, an automatic sealing device, a grain bag sliding conveying platform and a control system, wherein the input end and the output end of the grain bin and weighing system are connected with the control system, and the output end of the control system is separately connected with the input ends of the bag taking and bagging mechanism, the automatic grain bin opening and closing mechanism, the bag opening auxiliary device, the automatic transmission mechanism and the automatic opening sealing device. The automatic bagging device not only can realize a function of automatically bagging grains, but also can realize automatic opening sealing and automatic transportation functions on the grains, so that a fully automatic production process is realized on the grains from bin discharging to packaging and transportation. The automatic bagging device not only greatly reduces labor force and increases the work efficiency, but also ensures bagging weight precision, thereby having wide popularization significance.