The effect of magnesium content and different thermomechanical treatment regimes on structure formation for sheet aluminum alloy AA5754 produced by twin-roll casting technology is evaluated. Cast sheets of alloy AA5754 containing 2.8, 3.0, and 3.2 wt.% magnesium 6 mm thick are cold rolled to a thickness of 1 mm. Three thermomechanical treatment regimes and annealing for alloy AA5754 are studied. Specimens obtained by this technology are strength tested. Grain size and distribution within the structure of finished sheet workpieces are determined by a standard procedure. With an increase in magnesium content in specimen grain diameter is considerably reduced. All specimens, prepared by a supplementary production scheme using homogenizing heat treatment in the final annealing stage, have maximum ductility, and also higher values of ultimate and yield strength than for specimens prepared using other production schemes and changed magnesium content.