To address the issues of trailing signals generated by ultrasonic transducers under excitation pulses and reverberation interference caused by multiple reflections and scattering of acoustic waves on the tank wall, which lead to a large blind zone in ultrasonic ranging, this paper proposes the use of Linear Frequency Modulated (LFM) waves with anti-reverberation capability as the transmit signal. Furthermore, aiming at the problems of image spectrum generation resulting in target detection ambiguity and high computational load when traditional receivers directly acquire real signals, quadrature demodulation technology is adopted at the receiver end. This approach not only obtains complex signals with strong anti-interference capability but also reduces system costs. By analyzing the reverberation model of the ultrasonic level meter and comparing the ambiguity function and Q-function of CW and LFM waves through simulation, this paper concludes that LFM waves possess superior target resolution capability and better anti-reverberation performance when the target is stationary. Experiments were conducted using LFM waves as the transmit signal. At the receiver end, complex signals were obtained via quadrature demodulation, followed by matched filtering. Experimental results demonstrate that the maximum absolute measurement error of this method is less than 4 mm, and the blind zone can be reduced to 8 cm, indicating high practical value and engineering significance.