Abstract: The additive manufacturing of aluminum matrix nanocomposite has the advantages of one-time forming and high design freedom of materials. While, the complexity of the preparation process caused by the introduction of nanocomponents and fracture behavior still need to be deeply studied. Taking the introduction of AlN nanoparticles as an example, SLM additive manufacturing technology was used to fabricate the AlMgScZr composite with different AlN contents. The formability and the fracture of the composite were analyzed. The results show that the AlN/AlMgScZr aluminum matrix composite has good SLM formability, when the lase power is 280 W, the scanning speed is 1200 mm/s, and the scanning spacing is 70 μm, the SLMed AlN/AlMgScZr composite own high density of 99.65%. The room temperature tensile properties of the composite with different AlN content do not change dramatically, the tensile strength of the deposited AlMgScZr sample is 370 MPa and the elongation is about 22%. The addition of AlN increases the core of dimples formation, and increases the number of dimples in the fracture, but the maximum size of dimples is smaller than that of the AlMgScZr alloy. The plastic deformation mostly occurs in the initial stage of dimple nucleation and growth, when a large number of dimples grow and connect before reaching larger size, the material breaks.