<p>The hot tearing susceptibility (HTS) of Al–<i>x</i>Mg–(3−<i>x</i>)Si alloys with Mg/Si ratios of 1, 1.5, 2, and 2.8 was evaluated using a “T-shaped” mold equipped with a thermocouple and a load cell, which were connected to a data acquisition system. The solidification process and hot tearing tendency of the alloys were simulated using ProCAST numerical simulation software. Subsequently, the experimentally obtained solidification characteristic parameters were brought into the optimized Clyne–Davies model to determine the HTS of the alloy, and the trends were consistent with the simulation results. The results showed that the HTS of the alloy decreased and then increased with increase in Mg/Si ratio and was lowest at Mg/Si = 1.5. Hot tearing usually starts at grain boundaries and the propagation depends on the evolution of thermal stresses during the cooling process. In addition, it is related to the feeding of the intergranular liquid phase and the precipitation of the second phase at the grain boundaries. All these aspects can be evaluated through the variation in the characteristic parameters during solidification. At Mg/Si = 1.5, the grain size of α-Al is the smallest and the volume fraction of the eutectic phase is the largest, resulting in the strongest ability to feed solid shrinkage in the late solidification stage. Furthermore, the precipitation of the Mg₂Si phase, which is similar to the matrix structure, can form intergranular bridges to improve the intergranular bonding and prevent the propagation of hot tears along the grain boundaries.</p>