The invention provides a grounding treatment method for a missile-on cable bundle shielding layer. According to the method, all shielded conductors in a cable bundle, required to be subjected to grounding treatment, are checked. After that, all shielded conductors in the cable bundle are processed according to steps. After the processing operation of the conductors, the conductors are checked, wherein the phenomena of wire breaking, wire missing and wire jumping in a shield braid, scratches, nicks and cracks in the insulating layers of shielded conductors, and the like are found out. All selected shield braids at one end of the cable bundle are straightened and pressed into a flat shape by means of a tool. After that, whether flattened shield braids are damaged or not is checked. The technical problem in the prior art that during the existing shielding layer grounding treatment, the insulating layers of conductors are easily punctured by the metal wires of shielding layers so as to cause the unreliable connection of shielding layers and grounding conductors can be solved. According to the method, based on the traditional processing method, an insulating tape is wound on the outerside of conductors. As a result, the insulating layers of conductors are effectively prevented from being punctured by shielding layers. The connection reliability of grounding conductors is effectively improved through the new connection mode of shielding layers and grounding conductors.