The disclosure provides a method, electronic device, and computer-readable storage medium for monitoring breathing activity. The method includes the following steps. A time series of incoming frames of a monitored subject is received and each incoming frame is spitted into multiple blocks, where each block of the time series of incoming frames with a same position forms a time series of incoming blocks. A motion vector of each block is computed and projected onto multiple non-parallel axes to be assigned a sign. The projected motion vectors of each time series of incoming blocks with respect to each axis are respectively merged into a corresponding 1D waveform and converted into a frequency domain, and an observe area is located accordingly. A breathing frequency of the monitored subject corresponding to the observe area is determined and whether or not the monitored subject is breathing abnormally is thereby determined.
