Embodiments of the present invention disclose a method and a device for transmitting a signal, and relate to the field of communications. The technical solutions provided by the embodiments of the present invention are: the method for transmitting a signal, including: determining a peak clipping threshold of a signal according to f(MCS), where MCS represents a modulation and coding scheme (MCS) of the signal, and f(MCS) is a corresponding relationship between the MCS and noise at a receiving end; performing peak clipping on the signal by using the peak clipping threshold to obtain a peak-clipped signal; and transmitting the peak-clipped signal. According to the embodiments of the present invention, different peak clipping thresholds may be selected according to different MCSs, and thus, the reliability of data transmission is improved.