The invention discloses a fast scanning circuit with the background current eliminating function. The fast scanning circuit comprises an alternating-current power source, a first operational amplifier, a second operational amplifier, a third operational amplifier, a fourth operational amplifier, an electrochemical cell, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, a first slide rheostat, a second slide rheostat and a first capacitor, a background currentcompensation generating circuit is formed by the third operational amplifier, the second rheostat, the tenth resistor and the first capacitor, and a background current eliminating circuit is formed bythe fourth operational amplifier, the sixth resistor, the seventh resistor, the eighth resistor and the ninth resistor. The fast scanning circuit has the advantages that no matter how the scanning frequency is improved, background currents are eliminated and do not cause interference or influence on Faradic currents, the signal to noise ratio of output voltage is increased, and the detection sensitivity of the scanning circuit is improved.