An internet protocol television (IPTV) receiving system and a method of processing data are disclosed. The IPTV receiving system according to present invention comprises a signal receiving unit for receiving an IPTV signal including respective scalable video streams for IPTV services of a plurality of layers including a base layer and at least one enhancement layer, the respective scalable video streams of the plurality of layers having different identifiers and program table information for the scalable video streams, a demodulating unit for demodulating the respective scalable video streams of the plurality of layers and the program table information of the received IPTV signal, a demultiplexer for identifying and outputting the demodulated video stream of the base layer with reference to the demodulated program table information and identifying and outputting the demodulated video stream of at least one enhancement layer, and a decoder for performing video decoding on a video stream of at least one layer identified and outputted by the demultiplexer.