A signal scrambling method and apparatus, and a signal descrambling method and apparatus are disclosed. In the signal scrambling method, a communications apparatus scrambles a signal by using a scrambling sequence, and sends the scrambled signal. In the signal descrambling method, a communications apparatus receives a signal, and descrambles the signal by using a scrambling sequence. An initial value of the scrambling sequence is determined based on a time unit number corresponding to a frame structure parameter used for transmitting the signal, so that different scrambling sequences can be used to scramble signals that are transmitted by using different frame structure parameters. Therefore, interference randomization can be implemented for signal scrambling, and this can be applicable to various application scenarios in 5G NR to improve performance.