In this work, a process-structure-property relationship for additively manufactured Al-Si-Mg alloy was constructed, with the aid of an integrated multi-physics model. Specifically, first, a series of thermal simulations were performed to understand molten pool geometry under different additive manufacturing (AM) operating conditions, including laser beam power, scanning speed, and hatch spacing. The porosity formation was predicted based on thermal simulation results, which yield molten pool dimension information for predicting the lack-of-fusion porosity. Dream.3D was utilized to reconstruct synthetic microstructures with different volume fraction of porosity. Following that, with microporosity data as input, a widely employed Elasto-viscoplastic fast Fourier transformation (FFT) formulation was utilized to identify the structure-property-performance relationship, e.g. in the form of stress-strain curves, thus successfully constructed a full process-structure-property-performance (PSPP) map for the Al-Si-Mg alloy. Finally, by taking advantage of the PSPP map, the effective improvement of mechanical performance of AM product was analyzed through optimizing AM manufacturing conditions.