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Purpose This study aims to investigate the influence of the gas-flow field distribution and design on the parts quality of 316L stainless steel and the vapor–spatter behavior. Design/methodology/approach Based on the hot-wire wind speed test method, the exact value of the gas velocity at different locations was accurately measured to establish the effect on the porosity and the mechanical properties of the parts. The influence of the placement of single or dual blow screens on the performance of the parts quality was also studied. Through scanning electron microscope and energy dispersive spectrometer, high-speed photography and other methods, the influence mechanism was explained. Findings It was found that too high or too low gas velocity both play a negative role, for 316L stainless steel, the range of 1.3–2.0 m/s is a suitable gas field velocity during the multilaser powder bed fusion process. And printing quality using dual blow screens is better than single. Practical implications The optimization of gas field design and optimal gas velocity (1.3–2.0 m/s) applied during laser melting can improve the quality of ML-PBF of 316L stainless steel. Originality/value This study showed the influence of the gas field on the spatter–vapor in the process during ML-PBF, and the unfavorable gas field led to the formation of pores and unmelted powders.