The cloud point is one of the characters for non-ionic surfactants and plays an important role in practical application. A new method for the determination of the cloud point by resonance light scattering was proposed. The cloud point of a pyrrolidone sample was determined by the new method and the results were compared with those of UV spectroscopy method and dynamic light scattering method. The cloud point temperatures measured by the three methods were 34.3℃, 31.7℃ and 34.7℃, respectively. Experimental results indicate that the cloud point temperature measured by resonance light scattering is very close to those by UV spectroscopy and dynamic light scattering.