The work aims to study micro-segregation of laser clad IN718 superalloy coatings fabricated under different atmosphere conditions. IN718 superalloy coatings were fabricated under different carrier gas and shielding gas conditions, and double-aging heat treatment was applied to the coating. Microstructure and characteristics of the coatings were analyzed using optical microscope (OM), structure and phase composition of the coatings were analyzed using scanning electron microscope (SEM) and energy disperse spectrometer (EDS), and hardness of the coatings before and after heat treatment was analyzed using Vickers hardness tester. Type of carrier gas had certain effects on the morphology and microstructure of the cladding layer, while type of shielding gas had no obvious effect. Compared with the coating prepared with argon (Ar) as carrier gas, the microstructure of the coating prepared with helium gas (He) as carrier gas was finer, the size of Laves phase was smaller and more uniformly distributed, volume fraction of the Laves phase decreased from 9.35% (Ar as carrier gas) to 5.25% (He as carrier gas), and Nb content in the Laves phase decreased from 20% to 16%, and hardness of the coating increased from 287HV0.2 to 306HV0.2. After the double-aging heat treatment, microhardness of the coatings was significantly increased. Hardness of the coating prepared with He as carrier gas was 468HV0.2, which was higher than that of the coating prepared with Ar gas as carrier gas (447HV0.2). Using He gas as carrier gas can effectively reduce segregation of Nb element in laser cladding IN718 coating, refine microstructure and increase microhardness of coating. However, He gas as shielding gas has no obvious effect on morphology and microstructure of coating.