Abstract: The study explores the effect of Fenpropathrin on the acute toxicity and Na⁺-K⁺-ATPase activity and histopathological changes of carp (Cyprinus carpio) gills.According to the acute toxicity result, the 96 hour lethal concentration (96 h LC₅₀) is 8.53 μg·L^-1and the safe concentration (SC) is 0.853 μg·L^-1.Exposed to Fenpropathrin at concentrations of 0, 0.43 μg·L^-1, 0.85 μg·L^-1, 1.70 μg·L^-1 and 4.27 μg·L^-1, the gill tissue of carp were collected at the 1^st, 3^rd, 7^th, 14^th, 21^st day, respectively.Results indicate that the activities of Na⁺-K⁺-ATP enzyme in gill tissue during different exposure periods vary in a wave shape, i.e., first decrease, then increase, and decrease again as the exposing time progresses at the same concentration.The ATPase activities reach the lowest at 3^rd day, which are very significantly different from the control (P < 0.01), with inhibition rates of 42.49%, 27.48%, 59.03% and 46.31%, respectively.The enzyme activities of all concentration groups reach the highest at 14^th day, which are significantly (P < 0.05) or very significantly (P < 0.01) higher than that of the control. At 21^st day, the enzyme activities of the highest concentration group are significantly lower than that of the control except the other 3 concentration groups.The HE staining histological changes in the gills include gill-amells distortion, epithelial cell and pillar cell shedding, blood capillary of gill-amells expanding and hyperaemia, mucilage cell and basal cell hyperplasia, sometimes even gill-amells adhesion and gill filament becoming club-shape.The damages of gill are related to concentration and effect of time accumulation.