The invention provides a wet sludge incineration method and a fluidized bed incinerator, and the problems that in the prior art, the structure is complex, and energy consumption is high are mainly solved. According to the wet sludge incineration method, underfeed type feeding is adopted, and existing treatment procedures are simplified. According to the fluidized bed incinerator, a pressure-bearing heat-adsorption heating surface is not arranged in the incinerator, partial wet sludge is directly put into the incinerator instead, and combustion heat is mainly absorbed by water evaporation heat of the wet sludge and solid and gas (including vapor and combustion flue gas) heating; and therefore, expenditure of construction is reduced, the quantity of sludge which needs to be dried is decreased, and high energy consumption caused by early-stage drying or filter pressing treatment of overall wet sludge is avoided.