[en] Distributed vibration sensing measurement with high frequency response is still a challenging task in distributed optical fiber vibration sensing systems. In this paper, a WDM based integrated scheme is proposed to directly demodulate the high frequency vibration signal with high spatial resolution by merging the phase sensitive optical time-domain reflectometry and the Sagnac interferometer. A maximum frequency response of ~2.5 MHz and a spatial resolution of 20 m have been achieved in a 4 km sensing fiber link. Comparison to conventional sensing structure, the proposed scheme shows great application potential in the field of distributed vibration sensing system. (paper)