Effective echo signal filtering is a waveform preprocessing step in airborne laser bathymetry. To address the low automation in effective echo filtering, we proposed an echo signal filtering method based on the K-means clustering algorithm. First, bathymetry signals were captured and saved as coarse signals using Matlab software. Subsequently, features such as maximum intensity, location of maximum intensity, and half-peak width were extracted from the coarse signals. Finally, K-means clustering algorithm was used to classify the samples, filtering out noise and abnormal pulse signals. The results show that K-means clustering is feasible for signal filtering, with noise signals filtering accuracy of 99% and abnormal pulse signals filtering accuracy of 95%, achieving standards comparable to manual filtering and significantly improving filtering efficiency. This method can further serve as a method for exploring preprocessing of a large amount of bathymetry signals.