The invention belongs to the technical field of 
mass spectrometry and particularly relates to a 
cascade mass spectrometry method performed in an 
ion trap 
mass analyzer. The 
cascade mass spectrometry method performed in the 
ion trap 
mass analyzer specifically comprises three stages of 
ion selective segregation, collision induction dissociation and mass scanning and analyzing. According to the 
cascade mass spectrometry method performed in the 
ion trap mass analyzer, in the stage of collision induction dissociation, by changing the period of a 
radio frequency signal, namely changing the frequency of radio-frequency 
voltage loaded on an 
ion trap, parent ions with a certain mass-to-charge ratio undergo 
resonance excitation so as to obtain energy. The high-energy ions which undergo 
resonance excitation collide with neutral molecules in the 
ion trap and are dissociated, outcome ions are generated, and the cascade 
mass spectrometry is achieved. The cascade mass spectrometry method performed in the ion trap 
mass analyzer has the advantages that only arrangement of 
software can be used for changing the scanning period of the stage of collision induction dissociation in order to achieve collision induction dissociation, and thus, an experiment device and a method of cascade mass spectrometry can be obviously simplified.