Abstract: The present invention relates to the technical field of mass analysis instruments. Disclosed is an ion excitation method in a linear ion trap. The method comprises: in a linear ion trap, and at an ion collision-induced dissociation stage, simultaneously applying an auxiliary excitation signal in radial X and Y directions thereof; increasing the kinetic energy of ions in the two directions, thereby increasing collisions with a center gas to cause dissociation; and converting the kinetic energy to internal energy to achieve tandem mass spectrometry analysis. The kinetic energy in the X and Y directions of the ion is increased, and compared to a conventional dissociation method in which ions are primarily excited in one direction, more kinetic energy is converted to internal energy, thus improving dissociation efficiency, shortening reaction time, and addressing a low mass cutoff effect in the ion trap.