The invention relates to the field of heat pipe structures, in particular to an ultra-thin heat pipe. The ultra-thin heat pipe comprises a pipe body, wherein the pipe body comprises a middle side wall and end portion side walls connected with the middle side wall, the inner wall of the middle side wall is provided with a metal powder sintering portion, the side, away from the middle side wall, of the metal powder sintering portion is provided with a plurality of evenly distributed protrusions, and steam channels are formed among the metal powder sintering portion, the protrusions, the middle side wall and the end portion side walls. The metal powder sintering portion is provided with the protrusions which are intermittently or continuously arranged, a groove is formed between every two adjacent protrusions, the groove-shaped fluid return channels are formed in the spaces formed by the grooves and the middle side wall, axial heat transferring ability of the heat pipe is effectively reinforced, additionally, due to arrangement of the protrusions, the porosity is increased, fluid return resistance in the heat pipe is reduced, heat transferring efficiency is improved, heat conductive performance of the heat pipe is reinforced, and meanwhile, materials and production cost are saved.