A PTRS sending method and receiving method and a communication apparatus. The method includes: a terminal device sends first information to a network device, receives first indication information from the network device, and sends a DFT-s-OFDM symbol to which a PTRS is mapped to the network device. In the method, a rule for mapping the PTRS to a plurality of layers of the DFT-s-OFDM symbol is specified, to ensure phase noise estimation performance and improve a demodulation capability.