The microstructure and stress state of the additive parts are improved by the combination of laser shock peening (LSP) and wire-arc additive manufacturing (WAAM) technologies. The microstructures, microhardness and residual stress distributions in the depth direction of 2319 aluminum alloys fabricated by WAAM before and after LSP are investigated. The research results show that LSP can significantly refine the grain size and improve the residual stress distribution of 2319 aluminum alloys fabricated by WAAM. After LSP, the average grain diameter of additive parts decreases from 68.86 μm before LSP to 34.32 μm, and the microhardness increases from 67.8 HV before LSP to 100.6 HV. The maximum residual compressive stress is about 90 MPa and the influence depth is 0.65 mm.