The main aim of the paper is to study the capability of a new environment p rotection agent called RC /XW which can dissipate warm fog. We chose anhydrous calcium chloride and sodium chloride as the contrast, the experiment on the capability of the three kinds of agentswas done under the same condition in the laboratory. The peak particle diameter of RC /XW is 12μm, and the anhydrous calcium chloride and sodium chloride particleswere crushed into four different scales: 10μm, 15μm, 20μm and 30μm. The conclusions are as follows: There is a very big difference in the fog dissipation effects for different kinds of agents or the same kind of agentwith different scales. The fog dissipation effect of agent is directly relative to its seeding dosage. The RC/XW is suitable to warm fog where water content ismore than 0. 3 g·m^{- 3} , and the seeding dosage must be bigger than 1 g·m^{- 3.}