The present invention manufactured mat by by relates to a piping groove forming method of the pad for a hot water mat and more particularly pressing the laminate formed by short fiber web laminate or randomly stacked to simultaneously form a groove for the pipe, in the manufacture heated mat pad of possible to prevent deformation of the convenience and the pad and that post-processing is related to the pipe groove forming method of the pad unnecessary warm water mat for forming the pipe groove again after production of formation sikimeuro pad the pipe groove upon pad manufacturing-environment, the present invention and the step of forming the laminate so as to have a constant thickness, the short fibers to form a random web or a layered laminated stack; Mould insert step of providing a metal mold provided with a projection for forming the hot water to the home frame body member to one side or both sides of water formed by the laminate and the laminate forming step; And a step of heating the mold and while the stack passing through the oven the heat of the high temperature heat supplied to the stack; Pressing the laminate is softened by the heating process to the pressurizing means to the pad forming step of the mold to one or both sides between the constant to reduce the thickness compression to form sikidoe pressing means and the stack is installed also pressed together to form a hot water groove and; Mold separation step of the process after forming the pad is compressed when the pad is formed to pass through the oven stripping the mold from one side or both sides of the pad; Coiling the hot water groove is formed in a roll or pad for hot water mat has its characterized by the manufacturing in a finishing process in order to cut into a predetermined size.