The invention provides a method for simultaneously determining various heterocyclic pesticides, degradation products and intermediates in water by liquid-liquid extraction/liquid chromatography. The method comprises the following steps of by using dichloromethane as an extractant, extracting a neutral water sample added with sodium chloride, extracting the target, drying, and concentrating the extract to obtain the target product; purifying the extract, and replacing the solvent with acetonitrile or directly replacing the solvent with acetonitrile; and separating and detecting by using a liquid chromatograph, carrying out gradient elution by using a ternary mobile phase or a binary mobile phase during separation, and quantifying by using an external standard method according to the qualitative retention time to obtain the concentration of each target object in the water sample. The method is efficient, easy to operate, low in detection limit, good in accuracy and precision and good inlinear relation, 16 heterocyclic pesticides, degradation products and intermediates can be detected at the same time, and problems that an existing heterocyclic pesticide detection method is not highin integration level, incomplete in target object coverage and even vacant, tedious in step and high in detection cost are solved; requirements of heterocyclic pesticide environment monitoring and management in China at the present stage are met.