Provided are a respiratory guiding device (100) and method used in respiratory gated ion beam irradiation, the respiratory guiding device (100) comprising: a respiratory signal detecting unit (101), for measuring a respiratory motion trajectory curve during free breathing and deep breathing, and a real-time respiratory motion position signal in the case of guided respiration a respiratory signal processing unit (102), for modeling free breathing and deep breathing according to an average respiratory cycle and an average respiratory amplitude calculated on the basis of the respiratory motion trajectory curve and setting a preset breath-hold time at the tail end of a function curve of a free breathing model and a deep breathing model to establish a respiratory guiding curve a control unit (103), for adjusting the magnetic excitation cycle of a synchrotron according to the respiratory cycle represented by the respiratory guiding curve during free breathing or deep breathing, thus synchronizing the magnetic excitation cycle of the synchrotron with the respiratory cycle. The device and method effectively reduce residual motion in a target region within a guided respiration window, and improve irradiation efficiency and precision of an ion beam.