The invention relates to a white smoke eliminating system for desulfurized smoke. The white smoke eliminating system comprises an air heating system and a smoke cooling system. The air heating systemcomprises an air blower, a flue heat exchanger and a first mixing box. The smoke cooling system comprises a dust collector, a lifting fan, a desulfurization tower, a condenser, a second mixing box anda chimney. In the air heating system, air is sent into the flue heat exchanger at the tail of an air preheater through the air blower to be subjected to heat exchange, heated into high-temperature air, and then introduced into the first mixing box. In the smoke cooling system, boiler smoke comes out from the air preheater and is sent into the desulfurization tower through the dust collector and the lifting fan to be desulfurized, and wet saturated smoke exhausted from the desulfurization tower contains water vapor and gypsum droplets, is cooled through the condenser to precipitate water droplets and the gypsum droplets, and meanwhile becomes wet saturated clean smoke at the lower temperature. The wet saturated clean smoke is introduced into the second mixing box to be evenly mixed with the high-temperature air introduced into the first mixing box, the temperature rises, the mixed smoke becomes unsaturated dry smoke to be sent into the chimney and exhausted into the atmosphere, and thus white smoke is prevented from being generated.