A new magnesium alloy containing gadolinium, yttrium, samarium, antimony, and zirconium was created using casting technology. After heat treatment, the microstructure of the alloy was studied. The alloy showed high tensile strength at 523K (around 250°C), reaching 345.5 MPa. As the temperature increased from 293K to 523K, the alloy became stronger due to increased deformation resistance and crack resistance, leading to an unusual temperature-dependent behavior in its strength.