Aiming at the problem that the low SNR speech endpoint detection accuracy is seriously affected by the background, a speech endpoint detection method based on projection classification is proposed in this paper. Firstly, the phonetic characteristics of low SNR environment is calculated using long speech signal rate measure characteristics. The method makes full use of different speech signal and a voice signal to enhance the degree of differentiation of low SNR condition. Secondly, by using Fisher criterion, the classification identification of the voice and the background noise is carried out to ensure that the projection parameters have the smallest similar characteristics and the largest different characteristics. The experimental results show that the proposed method has high detection accuracy, the correct detection rate is more than 86.7% even in the SNR=-10 dB white noise interference condition.