We reported here a novel procedure for preparing 2.5% beta cypermethrin/polyacrylate nanocapsules using miniemulsion polymerization method, in which formulation the stearic acid (SD) as assistant stabilizer and fatty alcohol-polyoxyethylene ether (n=9) sodium sulfate (AES) as emulsifier. The nanocapsules were characterized by IR, UV, transmission electron microscopy (TEM), laser particle size analyzer and TGA. It proves that beta cypermethrin nanocapsules have uniform size and core-shell structure, and the mean size is 49.1 nm. The encapsulation efficiency of nanocapsules is 84.6% and the loading capacity of nanocapsules is 13.4%. The analysis of FTIR and UV show there are no toxic organic solvent and benzene adjuvant existing in the formulation, therefore, the nanocapsule is eco-friendly. TGA analysis indicates the nanocapsule possesses release-controlled performance and could extend the duration.