The invention relates to a method for catalytic oxidation conversion of levulinic acid and levulinic acid ester. The method adopts air or oxygen as the oxidant, and a bivalent manganese compound and nitric acid, nitrate or nitrous acid, nitrite are employed as a composite catalyst to catalyze levulinic acid or levulinic acid ester liquid phase selective oxidation and esterification reaction under mild conditions, thus obtaining succinic acid diester. The method has the characteristics of high catalytic oxidation efficiency and mild reaction condition, the bivalent manganese compound and nitric acid, nitrate or nitrous acid, nitrite involved in the composite catalyst are cheap and easily available, and the product is easy to separate and purify, so that the method has very good practicability and broad application prospects.