With the rapid development of the economy, social security has become quite important. At the same time, the criminal methods used by criminals are more complicated and high-tech. Traditional security measures are mostly based on electrical sensing or relying on human surveillance, and are hard to guarantee people's property and personal safety effectively. Therefore, this study proposes a fiber perimeter system based on double M-Z structure, which uses the characteristics of the fiber to identify the pattern of interference signal, and then uses the special structure of entire perimeter system to respond to the interference signal with high efficiency and alarm, and even complete accurate positioning function. Through the signal processing technology, the signal-to-noise ratio of the acquired signal is increased, and a good recognition rate and a high positioning accuracy are achieved.