The present invention relates to a manufacture method of a frequency doubler. The method comprises a first step of manufacturing a frequency multiplier circuit board; a second step of washing a cavity; a third step of debugging electrical property; a fourth step of mounting the cavity; and a fifth step of retesting the electrical property, printing a logo, and completing manufacturing of a product. The manufacture method comprises manual welding and bonding steps, so that the process is simple, device investment is small, manufacture stability and quality consistency are high, and the method is applicable to mass production.