The invention relates to a distributed type optical fiber sensing system and a control method thereof. The system includes a high-speed A/D parallel acquisition unit, a digital down converter, a parallel accumulative averager unit and a signal extraction and calculation unit which are connected in return. According to the technical scheme, various kinds of noise interference introduced by multipleexternal functional modules in a traditional scheme are reduced, the integration degree of the system is increased, the time of signal analysis is greatly shortened, and thus the stability and reliability of the distributed type optical fiber sensing system are improved.