Abstract: Base on the fluorescence spectrum characteristic of polyhexamethylen guanidine hydrochloride(PHMG-HCl) reacting with ninhydrin, a new analytical method was established to determine polyhexamethylen guanidine hydrochloride in disinfectant. Determination of fluorescent product, the wavelengths of excitation and emission were 405 nm and 500 nm, respectively.In the existence of amphoteric surfactants, the fluorescence intensity was enhanced. And the intensity was linearly related to PHMG-HCl concentration in the range of 2.010-4～2.510-1g/L (r=0.9993). The detection limit was 4.010-5g/L Series of standard solutions and disinfectant samples were determined, and the rusults were satisfied.