This application provides a method for determining a reference signal sequence, a terminal device, and a network device. The method includes: receiving, by a terminal device, first indication information sent by a network device; determining, by the terminal device, a target resource based on the first indication information; determining, by the terminal device, a reference signal sequence based on parameters of a first bandwidth and parameters of a second bandwidth; and sending or receiving, by the terminal device, the reference signal sequence on the target resource. Based on the method for determining a reference signal sequence provided in this application, the reference signal sequence can be determined based on the parameters of the first bandwidth and the parameters of the second bandwidth.