The invention provides a multi-parameter distributed optical fiber sensing system. When the system transmits a detection signal to an optical fiber, an acousto-optic modulator is used to modulate an optical signal generated by a light source into a periodic pulse light. The magnitude of pulses in the periodic pulse light is different. External vibration information is collected when the pulse amplitude is large. When the pulse amplitude is small, the external temperature and strain information are collected. When the external vibration information is collected, the light intensity change of a Rayleigh scattered light generated by the optical fiber is obvious. Non-linear noise introduced by a stokes light generated by the optical fiber can be avoided when the external temperature and strain information are collected. The accuracy of information collection can be improved. A single information acquisition channel can be used to realize distributed multi-parameter acquisition of vibration, temperature and strain. The structure is relatively simple. The production cost of the system can be reduced.