The invention discloses a composite catalyst for synthesizing dimethyl carbonate. The composite catalyst is characterized in that an ordered nano array structured oxide is taken as a substrate and a catalytic active ingredient is loaded on the nano array structured oxide substrate by using a sol-gel method, wherein a nano array is an aluminum, zinc, titanium or silicon nano oxide array; the active ingredient is one of a H3PW12O40/CexTi1-xO2 catalyst, an organotin catalyst, a titanium alkoxy compound, a copper nickel alloy, an alkaline catalyst, and a nickel, cobalt, manganese acetate catalyst, and X is 0.1-0.9. The composite catalyst is ordered in structure and good in catalytic effect. The invention also provides a method for synthesizing dimethyl carbonate by using the composite catalyst.