mirror carp, the acute toxicity and tissue injury of ivermectin for Songpu mirror carp was studied. Ivermectin was given by oral administration to Songpu mirror carp at the dosage of 1.30 mg/kg, 1.69 mg/kg, 2.19 mg/kg, 2.86 mg/kg, 3.71 mg/kg, 4.83 mg/kg, 6.27 mg/kg, 8.16 mg/kg respectively. Blank control and solvent control were sited also. After given ivermectin, the fish were investigated in 96 h; the dead fish were sacrificed at once. Through calculating by SPSS, the 96h LD₅₀ and 95% confidence of LD₅₀ of ivermectin for Songpumirror carp were 4.04 mg/kg and 3.42~4.80 mg/kg, respectively. The results show that with the increase of the dose, the number of red blood cells had no obvious change, the hemoglobin concentration had rised and the white blood cell count had decreased, according to analysis blood cell of the administration group and the control group. By histological examination, the results show that at the dose of 4.83 mg/kg after oral administration of ivermectin, the tissues of Songpumirror carp began to appear obvious pathological changes. Large doses of ivermectin after oral administration, the intestinal villis became necroticed and shed in intestinal cavity, liver cells were atrophied and hepatic sinusoid became larger, tubular epithelial cells became degeneration and necrosis, myocardial fibers became atrophy and degeneration. This study provided some important reference data and theoretical basis for using ivermectin in the process of Songpumirror carp cultivating.