The invention discloses a waste gas dust removing method and a dust removing agent. According to the method, dust-containing waste gas and an organic dust removing agent enter a dust removing tower respectively and are in contact with each other in the tower; at least partial water steam in the dust-containing waste gas is condensed, and the organic dust removing agent and condensed water are used for adsorbing solid particles, acidic pollutants, organic pollutants and / or heavy metal compounds in the dust-containing waste gas; and purified air is emptied or enters a subsequent process. The organic dust removing agent comprises toxin-free and high-boiling-point organic solvent compositions which are selected from two or more of edible oil, silicone oil, modified silicone oil, liquid-state asphalt oil, tung tree seed oil, liquid-state paraffin wax oil, mineral oil, palm oil and illegal cooking oil. By virtue of the method, dust (including PM100, PM10, PM2.5, relatively small particles and the like) in the waste gas can be effectively removed, and HCl, HF, dioxin, polycyclic aromatic hydrocarbon, other organic matters, heavy metal compounds and the like in the waste gas can be removed.