Abstract: Three friction pressures of 40, 80 and 100 MPa were selected for the linear friction welding (LFW)experiments of Ti17 titanium alloy.An optical microscope and a scanning electron microscope equipped with electron back-scattering diffraction were used to analyze the microstructure of the three joints.The results show that with the increase of friction pressure, the width of weld zone(WZ)decreases obviously, and the deformation degree of the thermo-mechanically affected zone (TMAZ)increases.When the friction pressure is 40 MPa, the temperature of WZ during welding is in the α+β phase region, and the WZ still has primary phase; when the friction pressure is 80 MPa, the temperature of WZ is higher than the β-transition temperature, and the WZ is composed of metastable β phase; when the friction pressure increases to 100 MPa, the temperature of WZ is lower than that of the joint with 40 MPa friction pressure, and the content of primary α phase is higher than that of the joint with 40 MPa friction pressure.In addition, continuous dynamic recrystallization occurs in the WZs of the three joints.The recrystallized grains of the joints with 40 and 100 MPa friction pressures are relatively small, and the recrystallized grain orientation of the joint with 80 MPa friction pressure is the most concentrated.