A kind of circuit based on square wave is designed to solve the problem of equipment corrosion caused by fouling in the pipeline. The square wave with variable frequencies is generated by AVR micro controller unit. After being processed through the driving circuit, the electricity signal driving the coil produces a magnetic field. Under the effect of electromagnetic, dirt ion is removed from the pipe wall. Experimental results demonstrate the square wave with the frequency conversion from 0 Hz to 6 MHz. The duty ratio is fifty percent and the driving power is 72 W. The equipment has high efficiency and wide applications and is easy to installation. Besides, the power consumption is low.