A detecting device and method for a capacitive touch screen is proposed. A plurality of frequency settings is employed. Each frequency setting corresponds to a type of driving mode of a type of driving potential. These frequency settings are used for setting the detecting device for the capacitive touch screen. When the signal-to-noise (S/N) ratio of the signals in the capacitive touch screen is not appropriate, frequency settings are changed by selecting one that yields a more appropriate S/N ratio among the frequency settings. The driving mode includes a single-electrode driving mode in which only a single driving electrode in the capacitive touch screen is driven at a time, and a multiple-electrode driving mode in which multiple driving electrodes are simultaneously driven at a time, and there can be several types of driving potentials.