The association particle systems of nicotine (NT)-PMo heteropoly acid were studied spectrophotometrically and resonance scattering spectroscopitrically. The absorbance values decreases with the wavelength in the range of 300-800 nm. The A400 nm is linear to the nicotine concentration in the range of 0.16～24 μg/mL. Its detection limit is 0.08 μg/mL NT. A new spectrophotometric method has been proposed for the determination of NT in real samples, with some advantages including high sensitivity, simplicity, rapidity and accuracy. The means recovery is 100.5%. The RSD is 1.00%(n=5). The results of resonance scattering spectra show that there are (NT-PMo)n association particles which exhibit resonance scattering effect at 420 nm.