A laboratory experiment was performed in order to dissipate the warm fog by using 6 kinds of hygroscopic catalysts of powdered rareearth salt materials in a 43 m3 warm cloud chamber. The microphysical characteristic data of warm fog, such as number concentration, diameters of fog droplets, and fog droplet spectrum,were continuously detected by a fog monitor (FM100). The fog transmissivity,temperature, and humidity of the cloud chamber were also continuously measured during every experiment process. Eight experiments, including two blank experiments (BE) of fog disperse spontaneously and six seeding experiments (SE) of fog seeding by using rareearth salts catalysts, were executed. The characteristic differences of warm fog in eight experiments are analyzed,and the effect and physical mechanisms of fog dispersal effect of 6 catalysts are studied through comparing measuring data between 2 BE and 6 SE. The experimental results show that 5 kinds of catalysts, including CeCl3, La(NO3)3, La2(CO3)3, LaCl3 and Ce2(CO3)3, can dispel warm fogs in the experiments,but Ce(NO3)3 can not achieve the effect of fog dispersal. There are differences in the effects on fog dispersal among five effective catalysts. The effects of CeCl3, La(NO3)3 and La2(CO3)3 are preferable,and those of LaCl3 and Ce2(CO3)3take second place. The analysis shows that the microphysical characteristics of warm fogs were obviously changed through seeding hygroscopic catalytic agents. The fog dissipation processes were accelerated or postponed because of seeding in 6 SEs.