An automatic assembly device having a rivet spinning riveting function and used for protectors comprises a workbench, a rotary disk, a rotary disk driving mechanism, a retained workpiece detection mechanism, a rivet mounting mechanism, a protector base extracting and releasing mechanism, a workpiece absence detection mechanism, a static contact mounting mechanism, a rivet spinning riveting mechanism, a movable contact extracting and releasing mechanism, a movable contact prepressing mechanism, a movable contact compressing mechanism, an inserting piece extracting and releasing mechanism, an inserting piece press-fixing mechanism and a protector removing mechanism. The automatic assembly device is characterized in that the rivet spinning riveting mechanism comprises a spinning head driving reduction gearbox cantilever support fixing column, a spinning head driving motor, a spinning head driving reduction gearbox, a spinning head, a press block lifting cylinder, a press block left limiting seat, a press block right limiting seat, a static contact press block and a pair of cylinder column fixing bracket guide rods. The automatic assembly device has the advantages that labor resources are saved, the operating intensity is reduced, the assembly efficiency is increased, the assembly quality is guaranteed, and the requirement for industrial mass production of refrigeration compressor motor protectors can be met.