Abstract: TDG-MS was applied to study the composition changing of blue gel pen inks on paper during artificial ageing at the time of this study. Mass spectroscopy was used to track and analyze the components of ion current for those compositions volatilizing easily from the blue gel pen inks on paper in the experiment. Research on artificial ageing for serials blue gel pen inks on paper under different conditions was performed in this paper. One of the key probes, glycol was found in the experiment, and the time-dependent changing of glycol was studied in the artificial ageing experiment. Principles and rules for glycol changing in artificial ageing of blue gel pen inks on paper substrates were concluded and discussed as well. The principles and rules can be used in the further research on relative ageing of documents written by various gel pens.