The invention relates to a transformant for producing 2,5-furandicarboxylic acid and a preparing method for 2,5-furandicarboxylic acid. The transformant includes a Pseudomonas putida and at least one exogenous gene, wherein the exogenous gene is an HmfH gene or an HMFO gene, and the exogenous gene is integrated into the chromosome of the Pseudomonas putida. The preparing method includes providing a reaction substrate including 5-hydroxymethylfurfural, and performing a fermentation step. In the fermentation step, the transformant for producing 2,5-furandicarboxylic acid is inoculated into the reaction substrate, and is cultured at a fermentation temperature for a fermentation time to obtain a fermented substance, wherein the fermented substance includes 2,5-furandicarboxylic acid. |