A low-density high strength Al–Mg–Zn–Cu alloy was designed and the thermal deformation behavior of spray-cast ingots was investigated. Using the Gleeble–3500 thermal simulation testing machine, the stress–strain curves of the spray-cast ingot under different thermal deformation conditions were measured. A strain-compensated constitutive equation was constructed, and thermal processing maps for the alloy at different strain levels were plotted. An Arrheniusbased constitutive equation expressed in terms of parameter Z showed a linear correlation coefficient of 0.995 between predicted flow stresses and experimental values, indicating an excellent fit. Analysis of thermal processing maps for various strains revealed that both the flow instability zones and regions with low power dissipation coefficients were concentrated in areas of high strain rates and high deformation temperatures. The optimal thermal deformation process parameters were identified as a temperature range of 380 – 420 ℃ and strain rate range of 0.001– 0.1 s–1. Within this optimal parameter range, the extruded strips of the spray-cast ingot exhibited microstructures in which internal porosity was mechanically welded without signs of flow instability. The density of the extruded strip was measured at (2.676 ± 0.006) g/cm3. After aging treatment at 140 ℃ for 40 h, the tensile strength reached (552 ± 8) MPa, yield strength was (423 ± 4) MPa, elongation after fracture was 13.5% ± 0.9%, and section shrinkage rate was 41.0% ± 1.7%. The alloy’s combination of high strength and low density suggests promising applications in lightweight structural components.