The capacitive touch screen uses the human body's current induction to work. The capacitive touch screen is a four-layer composite glass screen. The inner surface and interlayer of the glass screen are each coated with a layer of ITO, the outermost layer of which is a thin layer of silicon glass. The interlayer ITO coating is used as the working face, and four electrodes are drawn from the four corners. The inner ITO is the shielding layer to ensure a good working environment. When the finger touches the metal layer, because of the electric field of the human body, the user and the touch screen surface form a coupling capacitor. For the high frequency current, the capacitance is a direct conductor, so the finger absorbs a very small current from the contact point. This current flows out of the electrodes on the four corners of the other touch screen, and the current flowing through the four electrodes is proportional to the distance from the finger to the four corners. The controller calculates precisely the proportion of the four currents and obtains the position of the touch point.