The invention provides a dust removing blackboard eraser. The blackboard eraser comprises a sliding rod, a dust collecting device, a blackboard erasing device, a dust suction pipe and a dust outlet pipe, the dust collecting device is slidably connected with the sliding rod, the dust collecting device comprises a housing and a negative pressure device, the housing is internally provided with the negative pressure device, the negative pressure device is provided with a dust suction hole, a dust outlet and a gas discharging hole, and the blackboard eraser is provided a dust suction cavity, a duststorage cavity and bristles; the dust suction cavity is connected with a negative pressure chamber through the dust suction pipe to form a dust suction loop, and the dust storage cavity is connectedwith the dust outlet through the dust outlet pipe to form a dust outlet loop. The blackboard eraser has the advantages that the use is convenient and flexible, the dust removing capacity is high, timeand strength are saved when large-area erasing is conducted, and the targeting performance is high when the blackboard eraser is used for performing targeted revising on mistakes or small-area erasing.