This application provides an encoding method and apparatus in a wireless communications system. The method includes: performing cyclic redundancy check (CRC) encoding on A to-be-encoded information bits based on a CRC polynomial, to obtain a first bit sequence, where the first bit sequence includes L CRC bits and the A information bits; and performing polar encoding on the first bit sequence, where L has a value of one of 3, 4, 5, 8, and 16. Based on an improved CRC polynomial, coding satisfying a false alarm rate (FAR) requirement is implemented.