The invention discloses nylon-based high filling master batch and a preparation method thereof. The nylon-based high filling master batch is characterized by consisting of 20 to 40 weight percent of nylon-6 resin, 60 to 80 weight percent of filler, 0.1 to 0.5 weight percent of antioxygen, and 0.5 to 1.5 weight percent of lubricating agent. The preparation method comprises the following steps of: adding the nylon-6 resin, the filler, the antioxygen, and the lubricating agent into a high-speed mixer, and uniformly stirring; and adding a mixed material obtained in the step into a reciprocating single-screw extruder, extruding, cooling, drying and cutting into particles. The invention has the advantages that the content of the filler in the master batch can reach over 60 weight percent, the filler is uniformly dispersed in a nylon matrix, the master batch is accurate in ash content, and is suitable for modification and processing of nylon, and a nylon composite material with excellent performance can be prepared from the master batch. Moreover, the master batch has the advantages of simple preparation process, low cost and the like, meets the industrial production requirement and has wide market application prospect.