Embodiments of this application relate to the field of communication technologies, and disclose a communication method and apparatus, so that 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. A specific solution is as follows: 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.