This disclosure relates to methods and apparatus for detecting respiratory rate. The method for detecting respiratory rate may include: sampling respiratory waveform data in a time sequence detecting respiratory cycles from the sampled respiratory waveform data calculating variation degree for the sampled respiratory waveform data calculating base length base on the variation degree calculating smoothed length base on the base length calculating real-time degree for each respiratory cycle base on the variation degree, sequence number of each respiratory cycle, and the smoothed length and calculating respiratory rate base on the smoothed length and the real-time degree.
