AZ31 Mg alloy matrix composites were fabricated by squeeze casting method to improve high temperature properties in this study. The results showed that Mg composites reinforced with Alborex and Ag revealed improved high temperature properties and mechanical properties compared with Mg alloys. High temperature hardness and flexural strength were increased with reinforcement of Alborex, and further increase was obtained with addition of Ag. Also, Alborex reinforced AZ31 containing Ag Mg matrix composite exhibited greater improvement on creep properties. Therefore Mg composites reinforced with Alborex containing Ag were better than those reinforced with Alborex in mechanical properties and high temperature properties.