A motion-sensing floor mat, an assembly of such floor mats, and a monitoring system with such floor mats are provided； wherein the floor mat can be joined with another such floor mat and electrically connected to a monitoring device to form the monitoring system； the monitoring device stores a queue list and a topology matrix and uses a topological algorithm to store the identification tag of each such floor mat detected into the queue list in order, to gradually establish the topology matrix for the floor mats detected； and to thereby obtain the relative positions of the floor mats detected. When any of the floor mats is subjected to pressure (e.g., when someone falls on the floor mat accidentally) and generates a sensing signal, the monitoring device can pinpoint the position of that floor mat (i.e., the location of the fall) rapidly according to the topology matrix.
