An Internet broadcasting system and a method thereof are provided. The Internet broadcasting system includes: a signal converter for converting a received analog broadcasting signal into a digital broadcasting data; an Internet broadcasting unit for storing and sending the digital broadcasting data; a repeater for relaying the digital broadcasting data to a switching unit connected with a terminal according to a broadcasting request message inputted from the terminal but selectively relaying a channel selected by the terminal by referring to a first multicasting forwarding table created by using a UDP port number extracted from the broadcasting request message; and the switching unit for snooping on the broadcasting request message, extracting the UDP port number, storing the extracted UDP port number into a second multicasting forwarding table, and transmitting the digital broadcasting data of the selected channel to the corresponding terminal referring to an entry of the second multicasting forwarding table.