The invention relates to a preparation method of a lead-manganese oxide composite spherical palladium-loaded granular catalyst for synthesizing aryl carbonate by oxidative carbonylation. The method comprises the following steps: taking manganese carbonate and lead carbonate powder as raw materials, adding alumina sol, mixing uniformly, dropwise adding mixed slurry into an oil-ammonia column, ageing, washing, drying, roasting to obtain spherical carrier granules, and dipping the spherical carrier granules in a PdCl2 solution to obtain the spherical palladium-loaded granular catalyst. The method has the benefits that a synthesized spherical lead oxide and manganese oxide composite carrier has relatively high mechanical compressive strength which maximally reaches 54 N.cm<-1> and relatively large specific surface area which maximally reaches 100.2 cm<2>*g<-1>, and the catalyst prepared after the synthesized spherical lead oxide and manganese oxide composite carrier is loaded with palladium has relatively good catalytic activity, the DPC (diphenyl carbonate) yield which maximally can reach 12.01% and the selectivity higher than 99.1%.