Disclosed in the present application are a live broadcasting method and system for high-definition video transmission of a digital television. The system comprises: a descrambler device, connected to the digital television through a coaxial cable, for receiving a digital television signal inputted from the coaxial cable of the digital television and descrambling the digital television signal according to a descrambling command transmitted by a routing device to obtain corresponding descrambled signal data, wherein, the descrambling command is a command generated by the routing device after receiving a program playing command transmitted by an intelligent terminal; a routing device, for performing a signal extraction process with respect to the descrambled signal data to obtain a corresponding audio and video stream of a single program; and an intelligent terminal, for acquiring the audio and video stream of the single program through a data transmission channel provided by the routing device, decoding the audio and video stream of the single program using an own video decoder and playing the obtained signal after decoding. The present application improves the tidiness of field cable wiring on the basis of decreased acquisition cost of a user.