This study investigates the influence of impulse gas protection parameters on the mechanical properties of AZ91D magnesium alloy castings. Magnesium alloys are widely used in aerospace, automotive, and electronics industries due to their high strength-to-weight ratio. However, their high chemical reactivity during melting often leads to oxidation, spontaneous ignition, and contamination with non-metallic inclusions, which significantly reduces casting quality. To overcome these challenges, a pulsed gas protection system was developed and tested. Unlike traditional continuous gas shielding, the impulse method dynamically controls gas flow to optimize the formation and stability of the protective film on the melt surface. Experimental work focused on evaluating the effects of melt temperature, surface tension, and concentrations of SO₂ and SF₆ gases. Mechanical tests showed that these parameters have a significant impact on tensile strength, ductility, and hardness. Strength increased up to 285 MPa, elongation reached 3.1%, and hardness rose to 100 HB—all exceeding standard values for AZ91D alloy. A regression model was developed to predict these properties based on process conditions. The results confirm that impulse gas protection significantly enhances casting quality by minimizing oxidation and inclusions. The study provides a foundation for further optimization and broader application of this method in magnesium alloy casting.