The invention discloses an automatic mechanical arm sorting system based on image recognition. The automatic mechanical arm sorting system comprises a center control module. The center control moduleis connected with an operation setting module, a sorting executing module, an image collecting module, a weight weighing module and a pre-allocation module through a signal line. The operation settingmodule comprises a sorting frequency setting module, a sorting weight setting module and a sorting appearance setting module. The image collecting module collects the image appearance information ofworkpieces needing to be sorted, and the weight weighing module is used for weighing the weight of the workpieces needing to be sorted. Before sorting and in the sorting process, on the basis of robotvision shooting of the appearances of workpieces, a three-dimensional image is generated, the weight of the workpieces is weighed, attribute lists are generated before sorting and in the sorting process, recognizing and sorting are conducted on the different kinds of workpieces, and the disqualified workpieces are screened out; and sorting and screening are integrated, automatic running is conducted in the whole process, manual sorting is not needed, and the workpiece sorting and screening efficiency is improved.