Abstract: Speech endpoint detection is an important step in speech preprocessing.Its accuracy has an important impact on the speech synthesis and recognition systems.Based on the feature of formant-consonance energy,a scheme of speech endpoint detection is presented by taking advantage of image processing technology.This algorithm firstly gets rid of the periodic interference.Then it segments the spectrogram image after de-noising.Finally it derives the feature of formant and speech endpoint by using first order Gaussian differential filter.The experimental results indicate that it can get good quantitative results in the experiments within the environment of different SNR white noise and outburst noise.