The invention relates to an active detecting type fiber grating cable tunnel security and protection monitoring system. The active detecting type fiber grating cable tunnel security and protection monitoring system consists of a pump light source, a first coupler, a hydrophone, a low-frequency vibration sensor, an opto-isolator, a second coupler, a non-equilibrium Mach-Zehnder interferometer, a wavelength selector, a photoelectric detector, a piezoelectric transducer (PZT) driver, a digital acquisition device, a program gain control (PGC) phase demodulator and a computer provided with an alarm information managing platform. The active detecting type fiber grating cable tunnel security and protection monitoring system has the advantages of adopting a fiber grating sensor technology, being anti-electromagnetic-interference, electrically insulating, corrosion-resisting, good in safety, long in service life and easy to network, achieving remote distributed measurement and the like, has high sensitivity of an interference type demodulating system, can monitor sound inside and outside a cable tunnel and vibration produced by invaded people, reduces false alarm rate, improves identification on alarm events and operation safety supervision level of a power system and provides a safe and effective management mode for a power transmission system.