Abstract: Martensitic aging steel has high strength and high toughness, and is widely used in aerospace, petrochemical, Marine equipment and other fields. This article takes the 18Ni300 alloy as the research object and explores the forming consistency, densification and mechanical properties of 18Ni300 alloy fabricated by powder bed fusion under dual-laser. The results show that the variation trend of the density of the samples fabricated in different single-laser areas is basically the same. The response surface method was used to analyze the process parameters, and the relationship model between the density and the laser power, scanning speed and hatch distance was obtained, and the preferred parameters were determined. Under the preferred parameters, the mechanical properties of the 18Ni300 samples fabricated in the whole area are excellent and the difference rate is low. The tensile strength, yield strength and elongation of the samples in the single-laser area are 1186~1180 MPa, 1024~1034 MPa and 13%, respectively, and those of the samples in the dual-laser area are 1166 MPa, 1015 MPa and 12%, respectively. The difference rates of tensile strength, yield strength and elongation in the single-laser and dual-laser areas are 1.1%, 0.9% and 5.2%, respectively, showing good consistency. If the printing process was interrupted and continued, the tensile properties of 18Ni300 sample will be slightly reduced, and the step will be produced at the interruption.