The invention relates to a spin pulley welding machine tool which comprises a machine frame. A rotary plate driven by a driving mechanism is arranged on a table of the machine frame. Clamping mechanisms used for installing pulley shafts of spin pulleys are arranged on the rotary plate in a spaced mode. A jacking mechanism and a welding gun are arranged on one side of the table of the machine frame; when the clamping mechanisms rotate to a working station, the jacking mechanism is driven by a lifting mechanism to ascend so that the pulley shafts of the spin pulleys can be jacked up and rotated, and the welding gun is used for welding the pulley shafts of the spin pulleys. A discharging mechanism used for the pulley shafts of the spin pulleys is further arranged on the rear side of the table of the machine frame. The spin pulley welding machine tool is simple in structure and convenient for welding of the pulley shafts of the spin pulleys.