Provided in the invention is a differential voltage absolute value circuit comprising a first voltage-current conversion module, a second voltage-current conversion module, a first current subtraction module, a second current subtraction module, a current adding module, and a current-voltage conversion module. The two voltage-current conversion modules convert a first input voltage and a second input voltage into a first current and a second current; the two currents are inputted into the two current subtraction modules by a reversed connection way to obtain two difference currents; summation is carried out on the difference currents outputted by the two current subtraction modules by the current adding module to obtain an adding sum current, wherein the adding sum current is an absolute value of difference values of the first current and the second current; and then the adding sum current is converted into a voltage by the current-voltage conversion module to obtain a differential voltage absolute value of the first input voltage and the second input voltage. According to the invention, the provided differential voltage absolute value circuit has advantages of simple structure and low error.