A capacitive touch system uses at least two touch integrated circuits to simultaneously scan a touch panel, each of the touch integrated circuits only for scanning a portion of the traces of the touch panel. Therefore, the capacitive touch system can maintain a good frame rate, even the touch panel is a large scale touch panel. Sensing methods are provided to determine a sensed value for a boundary trace which is the last one of the traces connected to a first touch integrated circuit and prior to the first one of the traces connected to a second touch integrated circuit.