The desulphurization process by sorbent preparation system, absorption tower, recirculation system and automatic control system. Lower part of the flue gas from fluidized bed into the absorption tower, and hydrated lime particles fully mixed, SO ₂ and SO ₃ and other harmful gases, and lime hydrate reaction, generate CaSO ₃, 1/2 h ₂ O, CaSO ₄, 2 h ₂ O optimization and CaCO ₃. Process water with lower nozzle spray into the absorption tower, reduce the smoke temperature to increase the flue gas humidity, dew point temperature and water of the reaction temperature as close as possible to, so as to improve the efficiency of desulfurization. Reaction products by flue gas absorption tower from the upper to carry out, after the dust separation, separation down solid ash absorption tower air chute to circulation, ash circulating volume can be adjusted according to the load. In venturi reducing space formed by high-speed airflow and circulating ash and smoke desulfurizer solid particles and liquid droplets rapidly mix, formed in the reactor gas - solid - liquid phase flow. Recycling of the absorbent extended the desulfurization reaction time, improve the utilization of desulfurizer.