The present invention discloses a handheld device and a method for a handheld device to display synchronously with a TV set. The handheld device includes a display management module for converting output display data into data corresponding to a TV set screen resolution and displaying same on the TV set screen, and an output management module for converting the output display data into data corresponding to a handheld device resolution and displaying same on a handheld device screen synchronously with the TV set screen, the handheld device being connected to the TV set via an HDMI cable. A bidirectional synchronous display function is achieved in the present invention.