Method and apparatus for data processing in a multi-stream set-top box

An apparatus and a method for processing data in a multi-stream STB(Set-Top Box) are provided to select a TS(Transport Stream) corresponding to a broadcast program selected by a viewer and transmit only an MPEG2(Moving Picture Experts Group 2) TS corresponding to a paid program, which needs restrictive transmission, to a cable card, thereby preventing unnecessary data transmission and the unnecessary driving of the cable card in interface between the multi-stream STB and the cable card. A method for processing data in a multi-stream STB comprises the following steps of: allowing a terminal central processing unit to extract program information from SI(Service Information) whenever a viewer selects a new program(401,402); receiving a message related to the program(403); filtering the MPEG2 TS of a program which the message indicates(404); determining whether it is necessary to receive the MPEG2 TS restrictively(405); transmitting a TS stream, which needs restrictive transmission, to a cable card(406); and reproducing a TS stream having no need of restrictive transmission(407).