Ice-clad transmission lines can seriously damage a power grid to cause its partial or whole breakdown. Deicing the transmission line is a good method to prevent recurrence of such a situation. The development of DC-based deicing technology can make a difference for networks to fight the ice disaster. Based on the calculation and analysis of the transmission line deicing parameters， a DC-based deicing technical scheme for typical AC transmission lines in China Southern Power Grid is proposed. The development and application of DC deicer prototypes in China Southern Power Grid（CSG） is discussed， with those of 60 MW， 25 MW and 500 kW DC deicers addressed in particular， including their design， factory test， field test and the actual application effect.