A novel resonance light scattering method for the determination of PaH was developed based on the interaction of Palmatine hydrochloride (PaH) with Morin in pH 4.6 HAc-NaAc buffer medium, and this interaction can result in largely enhanced resonance light scattering (RLS) signal characterized by a peak at 308.0 nm. It was found that the enhanced RLS signals intensity (IRLS) at 308.0 nm is proportional to the concentration of PaH. The limit of detection is 8.0 nmol·L-1 and the linear range is from 0.08 to 1.0 mol·L-1. In this study, the mechanism of this reaction was investigated by scanning electron microscope (SEM), dynamic light scattering (DLS) and UV absorption spectrum. The SEM images and DLS graph show that ion-association complex aggregated after the addition of PaH. The experimental condition optimization results indicate that when the buffer medium is pH 4.6 HAc-NaAc without adding NaCl, the system has a good response for PaH. The authors investigated the stability of this system. The results indicate that this reaction system has a rapid response and the IRLS can reach the maximum within 5 min and remain stable at least for 120 min. The tolerance of coexisting foreign substances in the system was also studied. The research results show that the common metal ions, inorganic anions, a part of carbohydrate and amino acids have negligible effects on the analysis of PaH. This proposed method has some advantages including simplicity, rapidity and sensitivity. It also has been applied to the detection of PaH in tablet and capsule samples with RSD≤3.3%.