A method is provided for channel encoding in a communication system using a Low-Density Parity Check (LDPC) code. The method includes grouping information bits into a plurality of groups, determining an order of the plurality of groups to be shortened, according to a code rate, determining a length of information bits to be obtained by shortening the plurality of groups, shortening the plurality of groups on a group basis in the determined order, based on the determined length of the information bits, and LDPC-encoding shortened information bits.