Friction wear is a key factor influencing the life of friction stir welding (FSW) tools. One of the challenging problems in the field of FSW is improving anti-wear properties and extending the service life of tools. Based on Archard theory, a rigid-plastic mathematical-physical model describing the friction wear behavior of the tool during FSW process was established. The friction wear behavior and surface features of the tool during plunging and welding stage were studied by numerical and physical experiments. The effects of welding parameters and geometrical features of the tool on friction wear behavior were analyzed. 7075 aluminum alloy was chosen as the welding material and the tool was designed and manufactured by 3D printing. These numerical and physical experiments were compared. The results show that the tool fabricated from turning consisted of tempered martensite, while the tool produced from selective laser melting showed layers of banded structure with inhomogeneous directions. The average microhardness of the latter was higher than that of the former. The wear loss of the FSW tool during plunge stage increases with the increasing of the rotation speed and plunge speed. Meanwhile, the wear depth of the tool increases with raising the rotation speed at a constant welding speed. The weight of FSW tool decreases with increasing welding distance. The microstructure of the stir made by the selective laser melting is beneficial to improve the anti-wear property. The manufacturing process method can affect the tool’s lifetime seriously with the same material used. The simulation results are shown to be in good agreement with experimental data. The study also provides theoretical and practical guidance for predicting the wear of FSW tools.