A phase-sensitive optical time-domain reflectometric (Φ-OTDR) system based on the direct detection is demonstrated. It uses amplitude difference and two-dimensional Fourier transform method to extract the vibration information with a frequency response range from 5Hz to 2.5kHz, with a frequency resolution of 1 Hz, and the longest sensing length has reaches 9.8km. Then, a vibration positioning scheme based on hybrid Gaussian model is introduced, which is able to overcome the system error caused by laser power drift and successfully reduce the positioning error in the vibration-free region. A Φ-OTDR system based on the heterodyne detection is also proposed. Using self-mixing as demodulation method and the bilateral filtering algorithm in image processing as signal filtering method, this system preserves the information of vibration while filtering the background noise and improves the signal to noise ratio. Compared with the positioning result under direct detection scheme, there is a great improvement of result under this heterodyne detection scheme, and a better frequency response as low as 3 Hz is obtained.