Abstract: An adjustable effective electrode surface area stylus configured to operate with a capacitive touch sensitive device and coordinate detection method therefor is provided. The stylus comprises an electrode structure comprising a main electrode segment, a sub-electrode segment, a shielding, a switch, and a processing system. The main electrode segment has a main effective electrode surface area and the main electrode segment and sub-electrode segment together form an adjusted effective electrode surface area. The processing system drives the electrode structure to output one stimulation signal having one frequency and a flag and adjust between the output of a main projection of the main electrode surface area having a main central point and an adjusted projection of the adjusted electrode surface area having an adjusted central point. The main central point and adjusted central point projected from the electrode structure is used to calculate tilt and orientation of the stylus.