The invention discloses an electric dust collector which comprises a shell and at least one movable positive pole dust collecting device arranged inside the shell. The movable positive pole dust collecting device comprises dust collecting positive poles distributed in a loop mode, and a drive mechanism used for driving the dust collecting positive poles to move along the loop. The drive mechanism comprises a driving rotary shaft, a driven rotary shaft and a power source, wherein the driving rotary shaft and the driven rotary shaft are in pivot connection with the shell, and the power source drives the driving rotary shaft to rotate. The dust collecting positive poles are of a flexible belt-shaped structure tensioned by the driving rotary shaft and the driven rotary shaft. Due to the characteristic of power transmission of a belt transmission mechanism, drive power of the power source is converted into friction force between contact surfaces of the dust collecting positive poles and the driving rotary shaft so as to drive the dust collecting positive poles to move along the loop. Obviously, compared with the prior art, the electric dust collector has the advantages of simplifying the structure remarkably and then lowering the manufacturing cost. In addition, according to practical application, when the equivalent dust collecting efficiency is achieved, the weight of rolled steel consumed by the dust collecting positive poles is about 12.5% of that consumed in the prior art, and accordingly the overall manufacturing cost is further lowered.