Abstract: To compound aluminum alloy plate on the magnesium alloy plate is of great significance to broaden the application range of magnesium alloy. The compounding process test of magnesium alloy plate and aluminum alloy plate was carried out by explosive welding, and the magnesium alloy and aluminum alloy composite plate was fabricated by explosive welding. The optical microscope (OM) and scanning electron microscope (SEM) were used to observe and study the micro-morphology of the bonding interface of the composite board, and the formation process of the interface was analyzed. The hardness and shear strength at the bonding interface of the composite board were measured using a microhardness tester and a shear test machine. The results showed that the melting zone of the composite plate interface fabricated by explosive welding occurred solidified melts, and the structure was a mixture of Al₃Mg₂ and Al₁₂Mg₁₇ intermetallic compounds. The hardness of the melting zone was 126 HV, which was significantly higher than the substrate hardness (Al alloy 110 HV, Mg alloy 70 HV). There were differences in the shear strength of the specimens in the same sampling direction: the shear strength of the specimens cut along X axis shown a trend of first increasing and then decreasing, and the average value of the shear strength were 112.3 MPa (vertical to the explosion direction) and 87.0 MPa (parallel to the explosion direction); The shear strength of the specimens in the Y-axis direction was basically equivalent, which the value of the shear strength in average were 56.5 MPa (vertical to the explosion direction) and 61.0 MPa (parallel to the explosion direction).