The invention discloses a wet sludge drying method, a wet sludge drying drier and a cement kiln system. The method is characterized in that wet sludge is heated through high-temperature smoke gas, so that the wet sludge is dried to form dry sludge and smoke gas; the dry sludge and the smoke gas are respectively fed into a decomposing furnace of the cement kiln system. The drier comprises a revolving drum; the revolving drum is in rolling connection with a first double-roller bearing seat and a second double-roller bearing seat; the revolving drum is driven through a gear transmission device; the drier is provided with a high-temperature smoke gas inlet, a wet sludge feeding opening, a sludge smoke gas outlet and a dry sludge discharging opening. The cement kiln system is communicated with the drier, and the drier is communicated with a wet sludge discharging cabin. The thin wet sludge can be dried without combustion; dried sludge and gas are used as fuel and cement raw materials to be used; the heat value of the sludge can be fully utilized.