The invention discloses a material return anti-blocking device comprising a crushing barrel and a crushing cutter. The crushing barrel is arranged between a material return ash bucket of a desulfurization bag-type dust collector, and a discharge hopper. The crushing cutter is rotationally arranged in the crushing barrel and is used for crushing block materials entering the crushing barrel. Throughthe material return anti-blocking device, block lime falling from the material return ash bucket of the desulfurization bag-type dust collector can be crushed, the completely crushed materials fall smoothly from the discharge hopper, normal passing of circulation nitration lime on a subsequent channel is ensured, a material return conveying channel of a smoke circulation semidry method desulfurization system is smooth, and normal operation of the desulfurization system is ensured. The invention further provides the smoke circulation semidry method desulfurization system.