Embodiments of this application provide a method and a communications apparatus for hybrid automatic repeat request processing, and relate to the field of communications technologies, to help reduce the possibility that an exception occurs due to the introduction of a HARQ feedback mechanism in sidelink communication. The method includes: A first terminal device receives first sidelink grant information, a first HARQ process identifier (ID), and first indication information from a network device. If the first indication information indicates retransmission and a transport block corresponding to a first HARQ process has been successfully sent, the first terminal device ignores the first sidelink grant information.