Projection method and device

The invention provides a projection method and device. The method and the device are applied to a first terminal. The first terminal comprises a general purpose input/output GPIO. A projection sending end is arranged on the first terminal. When the first terminal is in a power-on state and a second terminal connected with the first terminal satisfies a preset state switch demand, the GPIO is controlled to output electrifying signals, thereby electrifying the projection sending end and a projection receiving end on the second terminal; after the projection sending end and the projection receiving end are electrified, the GPIO is controlled to output a paring signal, thereby pairing the projection sending and the projection receiving end; and after pairing is carried out successfully, the second terminal receives and outputs a video signal sent by the first terminal, thereby carrying out projection display. According to the method and the device, the problem that in the prior art, physical switches are arranged