Abstract: Paint pen as a new type of marker pen, with water resistance, light resistance, not easy to fade and other characteristics, suitable for writing, painting and marking on a variety of materials, more used in construction operations.Recently, inspectors have found that criminal suspects use paint pens to write slogans, threatening letters, etc., and the writing position is often located in the blind field of vision without monitoring coverage, which has brought greater technical challenges to investigators, caused extremely bad social impact, and affected the political ecological environment of clean air, but the practical community lacks relevant research on paint pens. Based on this situation, an experiment was carried out to simulate the actual case situation, and the handwriting of 25 writers on smooth objects with standing posture and paint pen was collected and compared with the normal handwriting. Through feature comparison and statistical analysis, the handwriting characteristics and change rules of paint pen handwriting are summarized, the characteristics of paint pen handwriting are correctly understood and analyzed, the theoretical framework of examination is enriched, and the "DNA" in the handwriting is found, which is conducive to the rapid screening and key investigation in such cases, and provides a certain reference basis for the identification and evaluation of related handwriting.