One of the most common wastewater pollutants is organophosphorus pesticides, which have a complex of properties-high solubility, toxicity, mobility in the environment. In recent years, this method has become an innovative analytical technology for the most part used in medical practice and in pharmaceuticals. With development, the method begins to acquire a practical application in other branches of human life activity. In this paper, the results of studies on the detection of Malathion (MLT) -O, O-Dimethyl-S-(1, 2-dicarbethoxyethyl) dithiophosphate in aqueous media is studied. The purpose of this study was to develop liquid chromatography and mass spectroscopy мethod for the determination of Malathion in water solution. This method will provide experimental results from testing conducted to evaluate sensitivity, selectivity, linearity, precision, accuracy, dilution integrity and various additional stability tests.