Methyl 3,3-dimethoxypropionate was prepared via the oxidation of acrylic acid by oxygen in methanol over PdCl2/CuCl2 catalyst. An acrylic acid conversion of 95.2% with a methyl 3,3-dimethoxypropionate selectivity of 90.6% was obtained at 35 degrees C and 5 atm. The reaction pathway might be that the esterification of acrylic acid in methanol was the first step, then methyl acrylate reacted with oxygen to form an intermediate aldehyde, which could react with methanol to form methyl 3,3-dimethoxypropionate.