The invention relates to the technical field of chemical catalysis, in particular to a magnetic nanogold catalyst for synthesis of ester through one-step oxidative esterification of aldehydes as wellas a preparation method and an application of the catalyst. The magnetic nanogold catalyst takes Au as an active component and a CeaFebXcO2 solid solution as a carrier, wherein the supporting amount of Au accounts for 0.1wt.%-2wt.% of the total mass of Au and the CeaFebXcO2 solid solution; in the CeaFebXcO2 solid solution, a is larger than 0 and smaller than 1, b is larger than 0 and smaller than1, c is larger than or equal to 0 and smaller than 1, the sum of a, b and c is equal to 1, and X is Co, Ni, Zr, Mn, Y, La, Cu or Zn. The aldehyde conversion rate is 97.5%-99.9%, the ester selectivityis 97.3%-99.0%, the catalyst has the characteristics of being simple to operate, higher in conversion rate and better in product selectivity, the catalyst is convenient to recover, and the reaction stability and the process economy are greatly improved.