A high-strength and high-toughness magnesium alloy includes a Mg—Al—Bi—Sb—Zn—Sr—Y—Mn alloy, prepared from the following components in percentage by mass: 7.0 to 10.0% of Al, 0.2 to 2.0% of Bi, 0.2 to 0.8% of Sb, 0.2 to 0.5% of Zn, 0.1 to 0.5% of Sr, 0.03 to 0.3% of Y, 0.05 to 0.1% of Mn and a balance of Mg.