Abstract: Laser power is a key influencing factor that affects the forming quality of Al-Mg-Sc-Zr high-strength aluminum alloys fabricated by selective laser melting(SLM). This paper studied the corresponding relationship between laser power and the forming quality of SLM-fabricated high-strength aluminum alloy, and analyzed the influence law of laser power on the microstructure and tensile properties of SLM-fabricated aluminum alloy specimens. The research show that incomplete fusion defects are prone to occur at laser power of 300 W, and the relative density increases with the increase of laser power; however, when the laser power increases rises to 420 W, excessive power leads to large porosity defects. Under different laser powers, the cladding layer of SLM-fabricated high-strength aluminum alloy specimens all presents a bimodal microstructure of columnar crystals inside the cladding layer and equiaxed crystals at the boundaries. With the increase of laser power, the size of columnar crystal increases gradually, while the tensile properties first increase then decrease. When the laser power is 360 W, the tensile properties of SLM-fabricated aluminum alloy reach the optimum,with the ultimate tensile strength, yield strength and elongation being 554 MPa, 537 MPa and 12.4%, respectively.