The principle of highlighter is to generate atomic energy level transition by absorbing light energy, and then release the absorbed excess energy. Some fluorescent agent was added to the highlighter. Some fluorescent substances are toxic and have potential carcinogenic components, which are harmful to human body after long-term use and are cheap. In order to reduce costs, some small workshops will use toxic fluorescent agents as raw materials for fluorescent pens. In addition, because highlighters contain a lot of fluorescent agents, long-term use will also seriously affect children's vision.