The invention relates to an automatic weighing system for fruits and vegetables. The automatic weighing system comprises a material lifting system, an automatic material distributing system, a control system and a material discharging system, wherein the material lifting system is used for conveying the materials to be weighed to the automatic material distributing system; the automatic material distributing system comprises a material distributing board and two sets of weighing and screening systems connected with the material distributing board; each set of weighing and screening systems comprises a material distributing slope, a first conveyor belt connected with the material distributing slope, a weighing hopper for receiving and weighing the materials on the first conveyor belt, a swing arm for controlling the supplying of the materials on the weighing hopper, and a second conveyor belt for conveying the materials in the weighing hopper to the material discharging system; the control system is used for controlling the motion of the first conveyor belt, the motion of the weighing hopper and the motion of the swing arm in the automatic material distributing system; and the material discharging system is used for transferring the materials conveyed by the second conveyor belt to a packaging system. According to the automatic weighing system disclosed by the invention, fully-automatic feeding, weighing and screening can be achieved, through controlling a weighing process and a screening process through the control system, the production efficiency is improved, and the labor cost is reduced.