Abstract: The TC4(Ti-6Al-4V)titanium alloy was plane milled precisely with PCD milling cutter. The flatness, the parallelism, the surface roughness, the surface hardness and the surface residual stress were measured by the coordinate measuring machine, the surface roughness meter, the micro Vickers hardness meter and the portable X-ray residual stress analyzer. The influences of different milling parameters on the quality and the surface morphology of TC4 titanium alloy were analyzed. The results show that with the optimal milling process parameters of spindle speed of 16 000 r/min, cutting depth of 0.2 mm and feed per tooth of 0.06 mm/z, the PCD milling cutter has a long life, and the TC4 titanium alloy workpiece has good surface quality and morphology. The flatness, the parallelism, the surface roughness, the microhardness and the residual stress of the workpiece are 0.26 μm, 0.64 μm, 0.63 μm, 3 080 N/mm² and -250 MPa, respectively.