The invention discloses an auxiliary tool for proportioning and adding sintering lime. The auxiliary tool comprises a left-right distributor and a material blending machine arranged on a belt conveyor. The left-right distributor and the material blending machine are separately located on the front and back sides of a lime blanking point. The material blending machine comprises a cross beam, two material blending arms and two material blending trays. The cross beam is vertical to the feeding direction of the belt conveyor and is arranged above the belt conveyor through supporting legs at two ends of the cross beam, the two material blending trays symmetrically lean against two sides of an upper material flow of the belt conveyor, the upper ends of the two material blending arms are connected to the cross arm, and the lower ends of the two material blending arms are rotatably connected to the two material blending trays through a bearing, separately. A material added to the belt conveyorforms a material ditch of a grate-layer material by means of the left-right distributor before the lime blanking point and the lime falling into the material ditch is buried by means of the materialblending machine, so that the lime can be prevented from being in contact with equipment such as a belt or a chute, and the hidden danger that the belt is deviated or the chute is blocked is eliminated. Diffusion of digestive heat of the lime can be prevented effectively, so that the digesting speed of the lime is improved.