Abstract: Effects of adding 0.5%,1.0%,1.5%Ce,La and Ce-rich MM to AZ91D alloy were studied.The microstructure and components of these alloys were investigated by scanning electron microscopy (SEM),energy dispersion spectrum (EDS) and X-ray diffraction (XRD).The hardness and tensile mechanical properties of room temperature and elevated temperature were also tested.The results indicates that either of Ce,La and Ce-rich MM can reduce the α-phase grain size,reduce the β-phase content and form needle-like Al11RE3 phase.When addition content is 1.0%,the room temperature and elevated temperature tensile strength of alloy arrived at maximum.Compare the alloys with different element but the same addition amount:the tensile strength of alloy with Ce is higher in low addition amounts condition;the elongation of alloy with La is greater in high addition amounts condition;the rigidity of Ce addition alloy is the highest,the rigidity of La addition alloy is the lowest.