The invention discloses an unpacking method of a plastic-packed metal wire bonding device, and belongs to the technical field of failure analysis of electronic devices. The unpacking method comprises the steps of performing flat grinding, cutting grooves and separating; when in flat grinding, the device is grinded through a 120-2000 meshes abrasive paper, wherein the grinding surface is the one plastic packing side of the active surface of a chip; the plastic packing material on the surface of the chip is gradually grinded and removed, and the grinding is stopped at the part being 0.5 to 3mm away from the chip surface; when in groove cutting, annular grooves are cut about the position of the chip, on the device grinding surface; when in separating, a plastic-packing material area surrounded with the annular groove is adhered through adhering materials, then the adhering materials are pulled until the plastic-packing material is pulled an separated from the chip surface so as to expose the chip. According to the method, the exposed internal chip of the device remains the bonding state of a first bonding point of a bonding wire, the corrosion and dirt close to the chip surface and the bonding part and other important information.