Laminar gas atomization technology based on Laval nozzle can efficiently prepare high-performance metal powders, but there is no systematic research on the process parameters and powder properties of this technology. In this paper, AlSi10Mg alloy powders were prepared by laminar gas atomization equipment based on Laval nozzle. At the same time, the effects of atomization gas pressure and tube inner diameter on the overall morphology, three-dimensional morphology, sphericity, particle size distribution, physical properties and internal defects of the powders were studied by traditional analysis methods and X-ray computed tomography technology. Combined with the numerical simulation of single-phase gas flow field and gas-liquid two-phase flow, the influence of process parameters on powder properties is explained. The results show that the performance of AlSi10Mg powders prepared by laminar gas atomization technology based on Laval nozzle is better than traditional gas atomization methods. Due to the higher gas pressure and narrow tube inner diameter, the gas-to-melt mass flow rate is higher, and the metal melt is more likely to be broken. Therefore, the powders have better sphericity, narrow particle size distribution, high fine powder yield of nearly 50%, and less irregular powders and hollow powders, The overall performance of AlSi10Mg alloy powders prepared by laminar gas atomization can meet the requirements of additive manufacturing.