The present disclosure provides techniques for determining a respiration phase by extracting a distance characteristic value, a score characteristic value, and an area characteristic value from the respiration signal, wherein the distance characteristic value, the score characteristic value and the area characteristic value are used to indicate waveform variation between two adjacent waveforms in the respiration signal. The techniques include training a respiration signal model according to the distance characteristic value, the score characteristic value, and the area characteristic value to determine the respiration phase of the respiration signal using the respiration signal model.