The invention discloses an air distributing device on a pulse bag type dust collector. The air distributing device comprises an air inlet and a lower box air chamber on the dust collector, wherein an air distributing plate is arranged between the air inlet and the lower box air chamber on the dust collector, and is arranged on a supporting angle iron which is fixed on a box body of the lower box air chamber by welding; and a bolt hole is processed in the supporting angle iron, and the air distributing plate is fastened by virtue of a bolt. The plate surface of the air distributing plate is uniformly provided with air inlets, and the air inlets are arranged in a staggered mode. The bore diameters of the air inlets are set to be 40-50mm. The air distributing device of the technical scheme is simple in structure, and the introduced air of the air inlet in the dust collector is uniform so as to enable each filter bag in the dust collector to receive same airflow, so that the dust collecting efficiency is greatly improved, and a dedusting effect can also be achieved at the same time.