The invention relates to a machining method for a non-vacuum maskless high-conductivity metal nanowire and belongs to the micro-nano machining field. According to the machining method, femtosecond laser is used for machining; firstly, reshaping is performed on incident laser light, so that a double-light-spot beam is produced; afterwards, the position of a sample is controlled through a three-dimensional displacement platform, so that the double-light-spot beam and the sample move relatively to form a machined pattern, wherein the line width is controlled by controlling a focusing plane and the surface of the sample. Based on the method, machining does not need to be performed under the vacuum condition, the requirement for the machining environment is lowered, and the cost can be reduced; a mask is not required, so the machining steps are simplified, and machining efficiency is improved; the metal nanowire is produced based on the mature electron beam evaporation method, no namometer clearance exists inside the metal nanowire, and the metal nanowire is high in conductivity; besides, the width of the metal nanowire can be adjusted within a large range. The machining method for the metal nanowire is reliable, efficiency and flexible.