An input method, comprising: displaying, by a display unit of a screen projection destination end that comprises the display unit, an obtaining unit, a sending unit, a receiving unit and an updating unit, a screen projection window in at least a part of a display interface, wherein the screen projection window is a mirror of screen display content of a screen projection source end, and the screen display content comprises a first edit box for receiving, accommodating, and editing input content; receiving, by the receiving unit of the screen projection destination end, input start information from the screen projection source end, wherein the input start information is used to indicate that the first edit box has obtained an input focus; obtaining, by the obtaining unit of the screen projection destination end in response to the input start information, text content or an image that is input by an input device of the screen projection destination end, to obtain to-be-displayed content; sending, by the sending unit of the screen projection destination end, the to-be-displayed content to the screen projection source end; and updating, by the updating unit of the screen projection destination end, the screen projection window, wherein an updated screen projection window is a mirror of updated screen display content of the screen projection source end, and the to-be-displayed content is displayed in the first edit box in the updated screen display content; before the receiving, by receiving unit of the screen projection destination end, input start information from the screen projection source end, wherein the input start information is used to indicate that the first edit box has obtained an input focus, the method further comprises: obtaining by the obtaining unit of the screen projection destination end, in response to a user clicking or tapping a mirror of the first edit box in the screen projection window, a click/tap signal for the mirror of the first edit box in the screen projection window, wherein the click/tap signal comprises a click/tap type and a click/tap location; and sending, by the sending unit of the screen projection destination end, the click/tap signal to the screen projection source end by using a reverse control channel, to enable the first edit box to obtain the input focus. displaying, by a display unit of a screen projection destination end that comprises the display unit, an obtaining unit, a sending unit, a receiving unit and an updating unit, a screen projection window in at least a part of a display interface, wherein the screen projection window is a mirror of screen display content of a screen projection source end, and the screen display content comprises a first edit box for receiving, accommodating, and editing input content; receiving, by the receiving unit of the screen projection destination end, input start information from the screen projection source end, wherein the input start information is used to indicate that the first edit box has obtained an input focus; obtaining, by the obtaining unit of the screen projection destination end in response to the input start information, text content or an image that is input by an input device of the screen projection destination end, to obtain to-be-displayed content; sending, by the sending unit of the screen projection destination end, the to-be-displayed content to the screen projection source end; and updating, by the updating unit of the screen projection destination end, the screen projection window, wherein an updated screen projection window is a mirror of updated screen display content of the screen projection source end, and the to-be-displayed content is displayed in the first edit box in the updated screen display content; before the receiving, by receiving unit of the screen projection destination end, input start information from the screen projection source end, wherein the input start information is used to indicate that the first edit box has obtained an input focus, the method further comprises: obtaining by the obtaining unit of the screen projection destination end, in response to a user clicking or tapping a mirror of the first edit box in the screen projection window, a click/tap signal for the mirror of the first edit box in the screen projection window, wherein the click/tap signal comprises a click/tap type and a click/tap location; and sending, by the sending unit of the screen projection destination end, the click/tap signal to the screen projection source end by using a reverse control channel, to enable the first edit box to obtain the input focus. obtaining by the obtaining unit of the screen projection destination end, in response to a user clicking or tapping a mirror of the first edit box in the screen projection window, a click/tap signal for the mirror of the first edit box in the screen projection window, wherein the click/tap signal comprises a click/tap type and a click/tap location; and sending, by the sending unit of the screen projection destination end, the click/tap signal to the screen projection source end by using a reverse control channel, to enable the first edit box to obtain the input focus.