Abstract: Thermo-sensitive pyraclostrobin microcapsules were obtained via emulsion polymerization successfully using poly(N-isopropylacrylamide-co-butylacr-ylate) as wall material. The morphology, the average diameter, the drug loading and the encapsulation efficiency of microcapsules were characterized by scanning electron microscope, optical microscope, automatic laser granularity analyzer, ultraviolet spectrophotometer. The performance of its controlled-release was studied by dialysis bag method. The acute toxicity of thermo-sensitive pyraclostrobin microcapsules to Brachydanio rerio was determined. The results showed that the obtained microcapsules had a smooth and spherical surface, and average diameter of thermo-sensitive pyraclostrobin microcapsule was 1.04 μm. The drug loading and encapsulation efficiency of thermo-sensitive pyraclostrobin microcapsules were 15.66% and 78.30%, respectively. The results also showed that pyraclostrobin microcapsules had representative temperature sensitivity, and the responsive temperature of microcapsule was 28.2 ℃. When the environment temperature was higher than 28.2 ℃, the microcapsule could release the active ingredient rapidly. When the environment temperature was lower than 28.2 ℃, its release behavior was restrained. The LC50 (96 h) value of thermo-sensitive pyraclostrobin microcapsules was 4.48 mg/L (active ingredient), it rised the LC50 (96 h) value of pyraclostrobin by 90 times, which significantly improved the security of pyraclostrobin to aquatic organisms.