The joined technique of dollop-like mischmetal and extruded Mg-mischmetal intermediate alloy in die casting Magnesium alloy AZ91D was investigated. Mischmetal absorptivity in Mg alloys was calculated. The results showed that the absorptivity of mischmetal achieved less than 50% within 30 min when mischmetal was added by dollop-like under conventional cold chamber die casting condition because the melting point of rare earth element exceeded the remelting temperature of die casting magnesium. The Mg-MM intermediate alloy was prepared by permanent mold casting and then was extruded into the bars. The microstructure and analytical studies were carried out using optical microscopy and differential scanning calorimetry （DSC）. Testing results shows the Mg-MM intermediate alloy could melt easily down at die casting temperature for RE containing Mg phase with lower melting point was formed and the mischmetal absorptivity was around 95% in laboratory. Then magnesium alloy test bars were produced under conventional cold chamber die casting condition with addition of extruded Mg-MM intermediate alloy and the mischmetal absorptivity was around 80%. Observation and analysis indicated that the microstructures of the alloy were refined and RE containing Al phase was formed.