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The microstructure and texture of FSP pure titanium in nitrogen atmosphere were investigated. The results showed that there were equiaxed grains in the stir zone. The average grain size of dynamic recrystallized grains near AS side and RS side was 2.29 μm. The combined effects of rising temperature and friction stir in the near surface and central zone, the average grain size grew to 6.48 μm and 8.64 μm respectively. The thermal-mechanical affect zone presented a gradient distribution. The grains near the stir zone had been seriously broken and refined. In the zone far away from the stir zone, the deformation of the original grains was slightly, and the deformation mechanism was dominated by deformation twinning. The width of the thermal-mechanical affect zone at AS side, bottom and RS side was 900 μm,700 μm and 480 μm respectively. The mainly deformation twins in the thermal-mechanical affect zone were {10-12} tensile twins. The structure of stirring pin was an important factor affecting the texture evolution of FSP pure titanium. Moreover, the c-axises of the grains in the stir zone were distributed close to the PD direction. Due to the combined effect of grain refinement and work hardening, the hardnesses in the stir zone were overall higher than the initial material, and the maximum hardness reached to 223.7HV0.5.