The invention provides a flue gas purifying absorbing tower and a processing method thereof. The absorbing tower comprises a tower body, an air inlet, an air outlet, an adsorbent feeding inlet, an adsorbent discharge hatch, an adsorbent layer, a feeding pipeline, and a discharging pipeline; the air inlet is arranged at the lower part at one side of the tower body, the air outlet is arranged at the upper part of the tower body with the same side of the air inlet, the adsorbent feed layer is vertically arranged in the tower body, the adsorbent feeding inlet and the feeding pipeline communicated with the adsorbent feeding inlet are arranged at top of the tower body, and the adsorbent discharge hatch and the discharging pipeline communicated with the adsorbent discharge hatch are arranged at the bottom of the tower body. The processing method comprises the following steps: the adsorbent is sent to the adsorbent layer through the adsorbent feeding inlet by the feeding pipeline, the flue gas is introduced into the tower from the air inlet, the flue gas passes through the adsorbent layer, and is discharged from the air outlet, and the adsorbent is discharged from the discharge hatch through the discharging pipeline. The inlet-outlet structure of the absorbing tower is capable of moving the adsorbent from top of the tower body to the bottom smoothly, the utilization rate of the tower body is guaranteed, the physical loss of the adsorbent is reduced, and the removal by adsorption can be efficiently carried out.