The invention discloses a piston type fiber bragg grating vibrating sensor. The piston type fiber bragg grating vibrating sensor comprises a vibrating body head, a vibrating body middle portion, a measurement grating, a vibrating body inner portion and a vibrator; a through hole and a groove are formed in one end of the vibrating body middle portion, and one end of the groove is connected with the vibrating body head; the vibrating body inner portion comprises a connecting rod and a simply supported beam, the measurement grating is connected with the simply supported beam, the simply supported beam is located in the groove formed in the vibrating middle portion and is connected with the vibrating body middle portion, the connecting rod penetrates through the through hole of the vibrating body middle portion, one end of the connecting rod is connected with the simply supported beam, and the other end of the connecting rod is connected with the vibrator. The piston type fiber bragg grating vibrating sensor is suitable for measurement of low-frequency vibration signals of huge buildings and water conservancy facilities, waterproof, moisture-proof, strong in electromagnet resisting ability, convenient to assemble, flexible in operation, adjustable in measuring frequency range, capable of reducing measurement errors and being manufactured easily, overall reliable, good in shock resistance and falling prevention performance, high in low-frequency signal restoration degree, and long in service life.