The work aims to complete surface modification by processing TC4 titanium alloy with Cu-SiC composite electrode prepared by ultrasonic electrolytic deposition and mixing carbon powder into working fluid, so as to obtain surface with excellent properties. TC4 titanium alloy was formed by using Cu-SiC composite electrode and Cu electrode. Firstly, morphology of the machined workpiece and fracture morphology of the melting layer were observed with scanning electron microscope (SEM), and roughness values in different positions on the surface were measured with TR200 roughness meter. Then microhardness of the workpiece‘s melting layer was measured with FM800 hardness tester, phase analysis of the strengthened layer was carried out by using X-ray diffractometer. Finally, electrode losses were compared and analyzed. The surface of TC4 titanium alloy machined by Cu electrode featured in deep and large pit, loose melting layer and poor adhesion. The surface of TC4 titanium alloy processed by Cu-SiC composite electrode featured in large traces of discharge, uniform depth, few discharge debris and compact melting layer. Measurement analysis from X ray diffractometer, FM800 hardness tester and roughness tester showed that workpiece surface machined by Cu-SiC composite electrode exhibited higher TiC peak, better abrasion resistance and higher hardness. The surface microhardness was about 6 times of the substrate, and average surface roughness value Ra was 2.825 μm. Loss of the composite electrode was 18% lower than that of copper electrode. The surface of TC4 titanium alloy is improved, surface of TC4 titanium alloy is improved, and the surface quality of Cu-SiC composite electrode subject to ultrasonic-electrodeposition is better than that of Cu electrode.