Ion trap performances are investigated based on digital ion trap technique with different collision gases at different pressures. Collision gases of helium (4 amu), nitrogen (28 amu) and argon (40 amu) with various pressures are adopted in ion excitation and dissociation stages to investigate the ion trap performances, including mass resolution, signal intensity, tandem mass spectrometric analysis ability and low-mass cut off (LMCO) effect. It is found that when heavy gas of argon is used, energy can be efficiently transferred and LMCO effect is decreased with higher ion capture and dissociation efficiencies but with low mass resolution. Higher mass resolution is realized with helium as collision gas. Furthermore, at the same gas pressure, heavy gas is beneficial to abundant fragment ions and structural information of precursor ion.