Triclopyr 2-butoxyethyl ester is a usual pesticide, however, its excessive use might pose risks to environmental safety. The rapid, simple and in-situ detecting method for triclopyr 2-butoxyethyl ester is of great importance but rarely reported. In this work, the first fluorescent sensor for triclopyr 2-butoxyethyl ester was developed based on a derivative of n-butyl-1,8-naphthimide Schiff-base (NSB). NSB is a typical AIE molecule with good green fluorescence in DMSO-H2O (5:95). The green fluorescence of NSB was transferred into strong blue fluorescence on sensing triclopyr 2-butoxyethyl ester. The high selective detection of NSB for triclopyr 2-butoxyethyl ester was observed among 26 kinds of normal metallic ions and pesticide molecules. The detecting limitation was as low as 2.89 × 10−7 M. The sensing mechanism was confirmed as 1:1 stoichiometric ratio based on the multiple hydrogen bonding and hydrophobic interactions. NSB was applied on sensing triclopyr 2-butoxyethyl ester in real samples of wheat seedlings, sugarcane and broadleaf weedane and water samples, suggesting the excellent application potential on simple, rapid and in-situ detection of triclopyr 2-butoxyethyl ester in daily environments.