Abstract: ADC12 aluminum alloy was modified by adding rare earth Ce.The effects of 0-0.9%Ce on the microstructure and mechanical properties of ADC12 aluminum alloy were studied by means of microstructure observation, tensile test and fracture morphology observation.The results show that rare earth Ce has good modification effect on ADC12 aluminum alloy.With the increase of Ce content, the area fraction of α-Al phase in the microstructure of ADC12 alloy increases first and then decreases, and the tensile strength and elongation of the alloy increase first and then decrease.The α-Al phase area fraction in the alloy with 0.5%Ce content reaches the maximum of 40.2%, and the tensile strength and elongation of the alloy also reach the maximum values of 258.2 MPa and 3.5%respectively,which are increased by 37.7%and 94.4%compared with those of the unmodified ADC12 alloy respectively.