The invention provides a heat-resistant magnesium alloy. The heat-resistant magnesium alloy is prepared from the following components in percentage by weight: 6-7% of Al, 0.4-0.7% of Zn, 0.4-0.7% of Mn, 1-2% of Nb, 1.5-2.7% of Zr, 0.2-1% of Ti, 0.5-1.3% of Co, 0.3-0.8% of V, 1-1.8% of B, 0.2-0.8% of Eu, 0.1-0.7% of Tb, 0.2-0.6% of Ce and the balance of Mg. Compared with the prior art, the elementsare combined to use, and the elements act with one another, so that high temperature resistance of the magnesium alloy is improved, and the magnesium alloy with good mechanical properties and high temperature resistance is obtained. According to the experimental results, the prepared heat-resistant magnesium alloy has the characteristics of excellent mechanical properties and high temperature resistance.