The utility model discloses a dual-FBG (Fiber Bragg Grating) vibrating sensor used for a liquid medium. The dual-FBG vibrating sensor is characterized by comprising a shell, a first FBG, a second FBG, a transmission optical fiber, a mass block, an L-shaped cantilever beam, a spring piece and a supporting fastener, wherein the first FBG and the second FBG are connected in series and are respectively connected with the shell through one end of the L-shaped cantilever beam, and the other end of the L-shaped cantilever beam is connected with the mass block; and the L-shaped cantilever beam is fixedly arranged on the shell by virtue of the spring piece. The dual-FBG vibrating sensor used for the liquid medium has self temperature compensation, and can be used for not only automatically eliminating influences of changes of environmental factors such as external temperature but also improving the detection flexibility and working band of the FBG vibrating sensor applied to vibration measurement.