This application provides a method for reporting port information, a terminal device, and a network device. The method includes: determining, by a terminal device, an uplink signal, where the uplink signal includes information about a phase tracking reference signal (PTRS) port of the terminal device, or the uplink signal includes information about the PTRS port and information about a demodulation reference signal (DMRS) port, or the uplink signal includes a correspondence between the PTRS port and the DMRS port; and sending, by the terminal device, the uplink signal to a network device. In embodiments of this application, the terminal device reports the uplink signal to the network device, so that the network device does not need to configure different PTRS ports for DMRS ports, to avoid configuring excessive PTRS ports, thereby saving PTRS port resources.