This article proposes a phone boundary detection method based on the spectrum. The spectrum is divided into three frequency regions according to the structure of the spectrum. The potential boundaries of every region are detected through the Euclidean distance between the neighbors of two vector frames of spectrums. The false phone boundaries are removed by a second examination. The phone boundaries are obtained via the fusion of the boundaries of three regions. Comparing with the method using phonological attributes，the computational complexity is significantly reduced，and a higher score of 3.95% is achieved