An embodiment of the present invention discloses a signal sending method, a signal receiving method, a terminal device, a base station, and a system, to ensure that a signal has a sufficiently large capacity when a PAPR is low, and reduce power consumption of the terminal device. The method in embodiments of the present invention includes: generating, by the terminal device, a first signal; performing, by the terminal device, code division processing on the first signal using a target code division sequence selected from a code division sequence set, to generate a second signal, where any two code division sequences in the code division sequence set meet orthogonality and shift orthogonality; and sending, by the terminal device, the second signal to the base station at a corresponding time-frequency resource location.