Abstract: Large cylindrical components of 2319 aluminum alloy with different cerium content （mass fractions of 0.07%, 0.23%, and 0.52%） were fabricated by a twin-wire cooperative arc additive manufacturing process, with ER2319 aluminum alloy wire as the primary wire and cerium-containing flux-cored aluminum wire as the auxiliary wire. The effect of cerium content on the microstructure and tensile properties of the components was studied. The results show that the microstructure of the alloys with different cerium content consisted of an α-Al matrix and secondary phases of Al₂Cu, Al₁₁Ce₃, and dislocation pile-ups appeared around the Al₁₁Ce₃ phase. When the cerium mass fraction increased to 0.23%, the number of Al₂Cu and Al₁₁Ce₃ secondary phases increased and their distribution became more uniform, and grains were refined; the yield strength, tensile strength, and elongation after fracture increased. When the cerium mass fraction increased to 0.52%, the total amount of secondary phases was reduced, and the grains were slightly coarsened; the tensile properties of the alloy decreased. The Al₁₁Ce₃ phase formed after cerium addition promoted heterogeneous nucleation due to their small average lattice mismatch （less than 12%） with α-Al, resuting in grain refinement. Second-phase precipitation strengthening made the primary contribution to the enhancement of the alloy’s strength, and grain boundary strengthening played a secondary role.