As to the application of the mobile sensor in the intrusion detections,one of the results is that the sensory areas are believed to be a specific shape,such as a circular or a rectangular. Because of this limitation,conclusions from a lot of relevant research are greatly confined to certain fields. In this paper,the sensory areas are proved to be a loop of different sizes,and a random model is designed according to the speed of the mobile sensor and the schedule and the number of its moving. Then,the detect...