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Reducing the defect density and improving the performance of selective laser melting-forming parts are significant for the development of selective laser melting (a great potential powder additive manufacturing method). Therefore, many methods like layer-by-layer laser remelting have been applied in the selective laser melting process. To investigate the influence of the layer-by-layer laser remelting process on the selective laser melting 316 L SS specimens, a three-dimension mesoscale remelting numerical simulation model in the single powder layer is established, and the microstructure and performance (surface quality, mechanical properties) are measured and analyzed with the different number of layer-by-layer laser remelting. The numerical simulation results show that the remelting process can effectively inhibit the defect. Nerversless, when the number of remelting is large, the over-melting phenomenon occurs, which is harmful to surface quality on the remelting surface. The experimental results also show that surface roughness, microhardness, ultimate strength, and strain can be effectively improved by controlling remelting times. [ABSTRACT FROM AUTHOR]