A pre-5th-generation (pre-5G) or 5G communication system for supporting higher data rates beyond a 4th-generation (4G) communication system, such as long term evolution (LTE) is provided. A channel encoding method in a communication or broadcasting system includes identifying an input bit size, determining a block size (Z), determining a low density parity check (LDPC) sequence to perform LDPC encoding, and performing the LDPC encoding based on the LDPC sequence and the block size.