Automatic ton bag packing machine using inverter stepless speed regulation to control the feeding speed. It can stably press down the material in the buffer silo, and at the same time discharge excess gas in the material through squeezing and conveying. The precision control valve can further improve the packaging accuracy. After the bag is loaded, the automatic ton bag packing machine automatically completes the work process of weighing, loosening the bag, unhooking, and conveying. The measuring form of the packaging machine is the gross weight weighing method under the measuring platform, and the structure is simple, stable and reliable. It is suitable for quantitative packaging of the limestone powder, talc powder, gypsum powder, mica powder, silica powder and other powdery materials with poor fluidity, large dust, and large air content.