In monitoring intrusion incidents based on phase-sensitive Optical Time Domain Reflectrometer(φ-OTDR), the methods of combining elements, which are the past records of a single point, the data of neighboring points, and the ratios of peak values, were introduced. The advantages and disadvantages of those methods by accuracy of identification, time consumption, complexity and stability were measured. The experimental results demonstrate the method combining the past records of a single point, and the data of neighboring points achieve the best performance, the identification accuracy rate can be as high as 100%, this method has a good adaptation in different frequencies. The research will contribute to the signal processing part of applying φ-OTDR to security system.