A communication method and apparatus are disclosed. According to the communication method, corresponding PDCP entities of a first terminal and a second terminal use consistent input parameters when executing security algorithms, thereby ensuring normal communication on a sidelink (SL) and improving communication reliability. In an example embodiment, a first terminal determines a logical channel identifier (LCID) meeting a preset condition, where a first packet data convergence protocol (PDCP) entity of the first terminal is associated with two or more logical channels (LCHs); the first terminal receives a first data packet from a second terminal; and the first PDCP entity of the first terminal parses the first data packet based on the LCID.