The quality of spot weld bonding in titanium alloy sheet metal was tested by using ultrasonic C-scan method. The specifics of the A-scan signals and the C-scan images were researched under different welding current. The tensile-shear tests were carried out to test the mechanical behavior of spot weld bonding.Results show that the characteristics of C-scan image and the change A-scan signal can divide adhesive, heat effected zone, melting area, nugget zone and weld defects. The nugget diameters of sport weld bonding increase with the increase of welding current, and the failure load average increase from 7 231.5 N to 10 939.0 N. When the current is 7 kA, it can get the information which includes splash and other weld defects from the ultrasonic C-scan image. The failure strength is less than the normal joints. The splash reduces the tensile shear load of the spot weld bonding joints.