In order to study the new method for the determination of hydralazine hydrochloride in pharmaceuticals, the light scattering intensity parameters of the reaction between hydralazine hydrochloride and sodium dodecyl benzene sulfonate were studied using the resonance light scattering spectrometry in Clark-Lubs buffer medium.The results showed that the reaction between the proper amount of hydrazinium hydrochloride and sodium dodecyl benzene sulfonate aqueous solution in the pH 1.4 Clark-Lubs buffer medium was π-π charge transfer and ion association reaction mechanism.The maximum emission wavelength of the resonance light scattering of the obtained product at 402 nm.The hydralazine hydrochloride concentration was linear in the range of 0.125 to 1.00 mg·L-1.The correlation coefficient R was 0.9998.The detection limit was 0.035 mg·L-1, and the recovery rate was 99.08~100.8%.The proposed method is suitable for analyzing the parametric relationship between hydralazine hydrochloride and light scattering intensity at room temperature, and can be applied to the determination of hydralazine hydrochloride in medicines.