A method for synthesizing 4-(Hydroxymethyl)benzoic acid using P-xylene (PX) as a raw material, including: dissolving PX in an organic solvent to undergo an oxidation reaction with an oxidizing agent under an action of an M-MOF catalyst; and after the oxidation reaction, performing a post-treatment to obtain the 4-(Hydroxymethyl)benzoic acid; wherein, the metal element M in the M-MOF catalyst is Fe, Cu, Cr, Mn, Cu/Fe, Cu/Cr, Cu/Mn, Fe/Mn, Cr/Fe or Cr/Mn. The by-product produced in the reaction process is little, the yield is high, and the separation is convenient. The acid-base neutralization is not required in the reaction process, reducing pollution. A one-step reaction is employed which has mild reaction conditions, short reaction time, low pollution and is convenient for industrialized mass production; and the obtained 4-(Hydroxymethyl)benzoic acid can be used for preparing medicines and liquid crystal materials having wide applications.