The traditional T6 heat treatment of ZL114A alloy is difficult to meet the increasing performance requirements of aerospace field. Therefore, a new low-to-high two-stage solution heat treatment process was designed in this paper, and the effects of single-stage solution treatment and two-stage solution treatment on the microstructure and mechanical performance of subsequent aged alloys were compared. The results show that the two-stage solution treatment increases the Mg concentration from 0.43 wt.% up to 0.54 wt.%, significantly improves the number density of Mg2Si aging precipitates, and promotes the intractable long strips π-Fe (FeMg3Si6Al8) phase which is difficult to eliminate in the single-stage solution treatment, into spherical β-Fe (FeSiAl5). At the same time, eutectic silicon particles with higher spheroidization were obtained. As a result, the mechanical properties of ZL114A alloy have been significantly improved: the ultimate tensile strength is 347MPa, the yield strength is 287MPa, and the elongation is 7.7%.