Surface nanocrystallization treatment of pure titanium TA2 was conducted by Supersonic Fine Particles Bombarding (SFPB) followed by heat treatment at different temperatures. The nanocrystallization mechanism and the thermal stability of TA2 sample after SFPB treatment were investigated by optical microscope (OM), X-ray diffraction (XRD), microhardness testing and transmission electron microscope (TEM). The results show that equiaxed nanocrystallites with random crystallographic orientations are obtained in the surface layer with SFPB, and the grain size is about 20 nm. During SFPB processing, deformation twinning is the main deformation mode in industrial pure titanium, and with the increase in the layer depth, twin deformation gradually changes from a multi-line system to a single one. In addition, when the annealing temperature is 450 oC, the grain size is below 100 nm and the sample has good thermal stability; when the annealing temperature is higher than 450 oC, the grains grow significantly (> 100 nm)