The invention relates to the field of metal product machining, in particular to a method for machining a boss through metal powder. The method comprises the following steps of (1) mold piling: placinga square mold with an upper opening on the corresponding portion of a mainboard, then putting the metal powder into the square mold and pressing the metal powder into a square block 5*10 mm through apressing block; (2) molding: taking down the mold, conducting scanning on the square block formed by the metal powder through a big laser spot to rapidly melt the square block and connecting and molding the melted square block with the mainboard to form a first boss; (3) grinding: grinding the molded first boss smooth through grinding equipment; and (4) conducting circulating: repeating the stepsof (1), (2) and (3), continuing forming subsequent bosses on the first boss until the height of the boss reaches the required height and then grinding the upper portion of the boss smooth through thegrinding equipment. Through the method, it is guaranteed that the normal function of the boss is not affected, and meanwhile, the material cost is saved.