The invention provides a synthesis method of 2,5-furandicarboxylic acid. The method comprises the following steps: 1. adding 2,5-dimethylfuran and N-bromosuccinimideintoan organic solvent, and carrying out bromination reaction under the action of an initiator to obtain a bromination product 2,5-dibromomethylfuran; and 2. carrying out oxidation reaction on the bromination product 2,5-dibromomethylfuran under the action of an oxidizer to obtain the 2,5-furandicarboxylic acid. By using the low-price 2,5-dimethylfuran as the raw material, the 2,5-dibromomethylfuran is firstly synthesized by bromination, and is oxidized by one step to obtain the high-yield target product 2,5-furandicarboxylic acid. The method disclosed by the scheme has the advantages of low cost and mild conditions, and is simple to operate.