Scented highlighter is widely used by primary and secondary students, but it is not certained that whether scented highlighter has toxicity. Therefore the first mass spectrometry analysis for the volatiles from the domestic scented highlighter was carried out. The volatiles emitted from the whole highlighter and each disassembled components were detected using solid-phase microextraction gas chromatography mass spectrometry (SPME-GC-MS). The experimental results showed that the highlighter odor arises from the ink inside. In four brands of mini highlighters, 15 kinds of volatile compounds were detected. Among them, high toxic acrylonitrile and banned additive ethylbenzene occurred in all brands. Using proton transfer reaction mass spectrometry online monitoring method, during highlighter wrote on the paper, the concentrations of acrylonitrile diffused to different height positions above the paper were determined. It is suggested that, as long as the distance from the paper is more than 20 cm, the infringement caused by inhaling poisonous odor can be effectively reduced.