N-{N-\[3-methyl-3-(3,4-methylenedioxyphenyl) butyl\]-α-L-aspartyl}-L-phenylalanine methyl ester is a new sweetener of neotame analogues. In this paper, to synthesize this sweetener, designed the strategy to obtain the key intermediate 3-methyl-3-(3,3- methylenedioxyphenyl) butyraldehyde. Use 3,4-methylenedioxybenzenboronic acid and 3,3-dimethylacrylic acid as starting material through Heck reaction, esterification and DIBAL-H reduction to get the intermediate successfully. Then the target sweetener was synthesized by the reductive amination of 3-methyl-3-(3,4-methylenedioxyphenyl) butyraldehyde with aspartame, which was catalyzed by palladium/carbon under the hydrogen atmosphere. The structure of the final product was identified by NMR, IR and HRMS, and the results matched with the desired sweetener. After being verified by sensory evaluation, the sweetness is about 30 000 times than sucrose.