The invention relates to a nut automatic packing machine. The nut automatic packing machine comprises a machine frame, a conveyer belt and a material weighing box. An automatic material falling device is arranged on the machine frame above the material weighing box, a weighing device is arranged on the machine frame below the material weighing box, and the portions, placed at the two ends of the conveyer belt, of the machine frame are respectively provided with a connecting rod in the feeding direction. The machine frame is fixedly connected with a pressing block, the machine frame is rotatably connected with a pressing plate, and an adhesive tape sealing machine is arranged on the machine frame at the tail end of the pressing block. The nut automatic packing machine has the advantages that nuts can automatically fall into the material weighing box through the automatic material falling device and can be weighed through the weighing device, the nuts are sequentially fed to the material weighing box through the conveyer belt, after the material weighing box is pressed by the pressing plate and the pressing block in sequence, sealing treatment is conducted on the material weighing box through the adhesive tape sealing machine, hence, the working strength of operating personnel is effectively lowered, the reliability of the material weighing box is guaranteed before the material weighing box is sealed, the pressing plate is controlled to rotate through an infrared sensor, the operating sensitivity is improved, and therefore the nut automatic packing machine is safe and reliable.