The invention relates to a dedusting device controlling PM2.5. The defect that dedusting devices in the prior art is non-ideal in PM2.5 removing effect is overcome. According to the provided dedusting device controlling PM2.5, smoke sequentially flows through a coagulator, an electric dust remover, a rotating electrode type electric dust remover, a wet desulfurizer and then is discharged. The coagulator is fixed to an inlet end socket or an inlet flue of the electric dust remover and comprises a pin fin. The coagulator can further comprises a charged device or an electric field mixing device. The rotating electrode type electric dust remover is deashed through a deashing steel brush. Compared with prior art, by arranging the pin fin, the smoke resistance can be reduced, particulate matter in the smoke can be advantageously coagulated, the size is increased after the particulate matter is coagulated, thus, the dedusting device can effectively remove dust in the smoke, and the dedusting performance of the dedusting device is optimized; and PM2.5 in the smoke can be effectively removed, and the dedusting effect of the dedusting device is improved.