The present invention relates to an improved synthesis of malathion. The presence of an acid facilitates the reaction between O,O-dimethyldithiophosphoric acid (O,O-DMDTPA) and maleate and leads to excellent product yield in shorter reaction time with fewer impurities.本發明係關於一種馬拉松(malathion)之改良合成。酸的存在促進在O,O-二甲基二硫代磷酸(O,O-DMDTPA)與順丁烯二酸二乙酯之間的反應,而帶來較短反應時間中的優異產物產率,且雜質較少。