The invention relates to the field of boat titanium alloy toughness investigation test materials applied to a boat titanium alloy application research and evaluation system, and particularly relates to a brittle weld bead surfacing welding wire for a crack source of titanium alloy applied to a boat and a preparation method of the brittle weld bead surfacing welding wire. The welding wire is prepared from the following elements and components in percentage by mass: 2.0-1.0 percent of aluminum, 3.0-6.0 percent of molybdenum, 5.0-10.0 percent of vanadium, 2.0-5.0 percent of chromium, 1.0-5.0 percent of tin and the balance of titanium. The welding wire provided by the invention can solve the problem about natural sharp cracks generated in a boat titanium alloy toughness investigation application process of a drop-weight test, an explosion test and the like, and thus the drop-weight test and explosion test methods for the titanium alloy applied to the boat can be improved, and the boat titanium alloy application research and evaluation system is more complete.