A virtual webcam applied in a computer includes a user interface application module for exchanging information between a computer and a user, so that a user can set parameter and format of a video signal source, select a special effect for a video signal, and select an output parameter and a format of a virtual webcam; a data processing module for processing special effects for the video signals transmitted from different signal sources and transmitting the video signals to the virtual webcam driver module; and a virtual webcam driver module for outputting the video signals according to the output format of a general webcam, so as to enable the outputted video signals to be used by a chatting tool and then shared by an opposite party over the Internet through the chatting tool.