The application provides a control method, device and system. The method includes the following steps: detecting signals in a circuit; responding to the circuit, detecting a loopback signal, and confirming that at least one part of a capacitive touch screen and a set of equipment form a loop by a user; responding to the formation of the loop, prohibiting or enabling functions corresponding to the at least one part of the capacitive touch screen. Through the adoption of the technical scheme provided by the application, through the detection of the loopback signal, the formation of the loop is confirmed, further the identity of the user is confirmed, and at least one part of functions can be prohibited or enabled; one mind operation of users can be effectively guaranteed in similar driving conditions, and safety is improved.