The invention relates to hot-dip cast aluminum alloy for anticorrosion treatment on engineering parts resistant to marine climate and a preparation method thereof, wherein said cast aluminum alloy contains Al, Zn, Si, Mg, RE, Ti, Ni and nanometer oxide particle reinforcing agent, said nanometer oxide particle reinforcing agent is selected from one or two of TiO2 and CeO2, the mass percentage of the components is as follows: Zn: 35-58%, Si: 0.3-4.0%, Mg: 0.1-5.0%, RE: 0.02-1.0%, Ti: 0.01-0.5%, Ni: 0.1-3.0%, and the total content of the nanometer oxide particle reinforcing agent: 0.01-1.0%; and the balance consists of Al and unavoidable impurities. The coating using cast aluminum alloy prepared by the invention has sufficient corrosion resistance and scour resistance in marine climate.