Selective laser melting (SLM)is an additive manufacturing technology which can be used to explore the near-net shaping of large components and net shaping of small complex structures. In this study, the microstructures and mechanical properties of SLM 18Ni300 alloy with variations of the aging time/temperature were investigated in details. Experimental results indicated that the tensile strength and micro-hardness of the SLM 18Ni300 alloy were increased due to the precipitations of the intermetallics during an aging treatment. When the aging temperature was 490 °C, the tensile strength of SLM 18Ni300 alloy increased significantly with the aging time prolong free of the softening, but the elongation decreased continuously. In order to improve the surface performance of SLM 18Ni300 alloy substrate, the mixed powders of NiCoCrAlY-SiC-Mo-Cu were deposited on the substrate (1 h, 520 °C aging treatment)by mean of a laser cladding (LC)technique. The production of the nanostuctured composites led its melting point to decrease, so the high interface energy of NPs became the driving force of the atomic motions, favoring a compact structure to be formed. Identification of the synthetic nanoscale particles (NPs)in such LC composites contributes theoretical and experimental basis to improve the quality of the laser 3D print materials.