Abstract: In order to meet the shielding requirements of γ-rays at the radiation hot spots of complex components during the shutdown and maintenance of nuclear power plants, a nylon/tungsten shielding composite material was developed suitable for the laser selective sintering 3D printing technology. The effects of the shielding performance of the 3D printing shielding material were emphatically studied for two preparation processes（including mechanical mixing method and coating method） of the 3D printing composite powder. The experimental results show that the coating method is preferred for the preparation of the 3D printing composite powder compared with the mechanical mixing method, which the product has better shielding capability. Experimental results show that the shielding material prepared by the 3D printing technology by the coating method is better than that by the mechanical mixing method in the shielding performance. By scanning the micro-fracture morphology with 400 times SEM, the tungsten powder is uniformly dispersed in the nylon matrix. The best formula of nylon/tungsten 3D printing shielding material was obtained by studying the performance of shielding materials with different ratios of 3D printing shielding material products, which met the shielding requirements of the plant and laid a theoretical foundation for the engineering application of the 3D printing shielding material.