Slip deformation in Ti-6Al-4V titanium laser welds was observed. Laser welding was used to prepare the titanium welds. Macrostructure, microstructure, mechanical property and structure of laser welds were studied using optical microscope, scanning electron microscope, compression experiment, transmission electron microscope （TEM） and high resolution TEM. Subsequently, slip deformation mechanism occurred in fracture and etched weld was discussed. The results indicate that the maximum compression strength reaches 1.191 GPa. Slip deformation easily happens in titanium laser welds and the minimum slip bands are 600 nm and 75 nm respectively in fracture and etched laser welds.
