Waveform sampling lidar is the technical tendency in lidar technology in virtue of its high precision of three-dimensional geodesy and multi-layer target detection ability. Especially, array detection imaging lidar systems applying the streak tube principle have promising application prospect because of their full waveform sampling and high degree of integration. A new lidar system which is based on full waveform echo sampling and array detection of the streak tube is established to extract noise in echo signal of airborne flight experiments and summarize statistical properties of echo noise. A new denoising method for echo signal in waveform sampling lidar is proposed by comparing the different statistical properties between noise and echo signals.