The invention provides a copolymerized nylon powder material used for selective laser sintering, and a preparation method thereof. The method comprises the following steps: carrying out a copolymerization reaction on a short-chain nylon raw material and a long-carbon chain nylon raw material by using a copolymerization reaction principle to obtain copolymerized nylon resin, carrying out cryogenic crushing, drying and screening on the copolymerized nylon resin, and adding a flow aid and an antioxidant to obtain the copolymerized nylon powder material used for selective laser sintering. The preparation method has the advantages of simple process and easiness in control, and copolymerized nylon powder particles have a narrow particle size distribution, can be well used in secondary molding, and is suitable for being used in the field of manufacturing of additional materials.