This paper presents the first report on employing fluorescent porous organic polymers as sensors for the detection of toxic pesticides. Specifically, fluorescent micro- and mesoporous polyaminals with pendant triphenyl-amine and dibromotriphenylamine chromophore groups are synthesized, which exhibit BET surface area up to 507 m(2) g(-1) adjustable pore sizes in the range from 0.5 to 36.2 nm and can emit bright turquoise light under the ultraviolet lamp. Using the insecticide (fenitrothion) and herbicides (trifluralin and glyphosate) as analytes, the chemosensing properties are investigated by correlating the porosity parameters and chemical structure of the polymers with the molecular sizes and the energy in the lowest unoccupied molecular orbital of pesticides. Moreover, the effects of different acid base conditions and solvents including ethanol, water, chloroform, tetrahydrofuran, and N,N-dimethylformamide on the chemosensing sensitivity of the polymers are also studied in detail. Particularly, the chemosensing test paper fabricated with the fluorescent polymer rapidly becomes dark upon contacting the pesticide solutions at an extremely low concentration, and the quenching degree is unchanged after repeating the experiments for 10 times, exhibiting the capability of sensible and reusable detection for pesticides.