The invention relates to synchronized dust removal and desulfuration for smoke of coal-fired boiler and comprehensive utilization of flyash of the coal-fired boiler. The dust removal and desulfuration processes for the smoke of the coal-fired boiler are performed in the same smoke washing equipment. The flyash which becomes smoke dust in the smoke is washed by washing and desulfurizing solution added with a sulfur dioxide liquid-phase catalytic oxidation catalyst and a cosolvent, and the formed flyash slurry realizes smoke dust removal. The sulfur dioxide dissolved in the flyash slurry is rapidly oxidized under the action of the catalysts to generate sulfuric acid for realizing the smoke desulfuration. The aluminum and basic oxides activated by the cosolvent in the flyash are reacted withthe sulfuric acid to give corresponding sulfate, and the aluminum element and some heavy metal elements are recycled through separation. Therefore, complete technology for the synchronized dust removal and desulfuration for the smoke of the coal-fired boiler and the comprehensive utilization of the flyash of the coal-fired boiler is formed.