The invention discloses a preparation method and device of a printed circuit. The method comprises acquiring a vector graph file; identifying a first vector graph source contained in the vector graphfile; Judging whether there is overlap between the first vector graph sources, and fusing the overlapped first vector graph sources to obtain at least one second vector graph source; generating a print trajectory according to the second vector map source; printing the molten low melting point metal on a printed substrate in a temperature environment not higher than the melting point of the low melting point metal according to a printing track to form a printed circuit; placing the printed circuit in a temperature environment not lower than the melting point of the low melting point metal to liquefy the flow level; solidifying low melt point metal again to obtain a printed circuit having a flat and uniform solid metal layer on that surface. By reintegrating the vector drawing source, the invention ensures that the problem of scratching the metal in the drawing process is avoided, and the problems of faults and burrs occurring in the printing of the solid metal at room temperature are eliminated by the method of secondary heating.