Lidar is an efficienttool for remote monitoring, but the effective range is often limited by signal-to-noise ratio (SNR). By the power spectralestimation, we find that digital filters are not fit for processing lidar signals buried in noise. In this paper, we present a new method of the lidar signal acquisition based on the wavelet trimmed thresholding technique to increase the effective range of lidar measurements. The performance of our method is investigated by detecting the real signals in noise. Theexperiment results show that our approach is superior to the traditional methods such as Butterworth filter.