Objective: Standardize the use of phoxim to ensure the safety of aquatic products. Methods: Taking freshwater crucian carp as the research object, Selecting phoxim, an organic phosphorus pesticide often used in agriculture, as the representative of exogenous environmental pollutants. The changes in normal physiological metabolism of crucian carp exposed to phoxim were studied by using the ¹H-NMR metabonomics method combined with PCA, PLS-DA, OPLS-DA and other multivariate statistical methods. Based on this, the toxic effects of phoxim on crucian carp and the toxicological mechanism of phoxim in the crucian carp were deduced. Results: Compared with the control group, the metabolites in the crucian carp serum sample of the phoxim group have a significant increase in concentration of 3-HB, glucose and phenylalanine, and a significant decrease of glutamic acid, alanine, asparagine, histidine, lactic acid, glycerol phosphate of choline, phosphoric acid, choline, choline and unsaturated fatty acids, lipids, guanine nucleoside, inosine(P<0.05). Conclusion: The results showed that phoxim can change amino acid metabolism, energy metabolism, disturbance of neurotransmitter balance and oxidative stress in crucian carp.and the endogenous metabolites change may be related to Ⅱ metabolic reactions of phoxim in crucian carp.