The signal processing circuit in pulse taut wire magnetic axis measurement system is improved in order to improve the measurement accuracy. Firstly, The reason of signal distortion is analyzed according to the amplitude frequency and phase frequency responses of the circuit. Then the theoretical computation results show that the Tilt error caused a 30 Hz square wave, and the Offest error caused an extra 5 ms pulse at the edge of the square. The proposed signal processing circuit, which can transfer signals from 30 Hz to 3 000 Hz undistortedly, satisfies the demands of this system. The measurement results show that the axis Tilt and Offest errors are easily to distinguish, and the measurement error is reduced.