The invention discloses a Synthesis of carboxylic ester. In neutral environment, using paraffin, naphthene, olefin, aromatic hydrocarbons or other low carbon hydrocarbon mixture as material, molecule oxygen as oxidant, one or multiple kind of single metalloporphyrin of general formula (I) or mu-oxidant bimetalloporphyrin of general formula (II), or their solid carrier as accelerant individually to be accelerant or the composite catalyst of they and metal salt or oxidate, the metalloporphyrin's concentration in accelerant is 1-100ppm; controlling the reaction temperature is 80-200deg C,reaction pressure is 0.1~2MPa., React for 1-10h, molecule oxygen firstly oxygenating hydrocarbon to carboxyl acid and alcohol, and then carboxyl acid and alcohol are further oxygenated to ester. This invention can completes oxidation and esterification reaction of hydrocarbon at the same time, has no pollution, no corrosion, the technique is simple, the raw material soure is broad, need not separate intermediate product, product's purity is high and can produce miscellaneous carboxylate.