This application provides a communication method and a communication apparatus. In the method, a terminal device sends, based on a first time domain resource, a preamble to a network device on a first RO that is in a first PRACH resource and that meets a first condition, where the first time domain resource includes a time domain resource used by the network device for at least one of data channel transmission or control channel transmission, the first condition is that a first time unit is in a first time window, the first time window is a window for monitoring a PDCCH that corresponds to an RAR that responds to the preamble, and the first time unit is a time unit that is in the first time domain resource and that can be used for transmission of the PDCCH corresponding to the RAR. In the method, the terminal device may select, based on the first time domain resource, an appropriate first RO from the first PRACH resource to initiate random access, to reduce a probability of random access failure of the terminal device caused by RAR window timeout. This method may be applied to an emergency ad hoc network.