Abstract: PM2.5 is a significant pollutant that seriously threatens human respiratory, circulatory, and nervous systems. Despite the deepening research, the PM2.5 analysis still faces challenges, with a number of the components not having been detected and identified. These hard-to-detect components are primarily semi- or medium-volatile organic compounds with boiling points above 200 ℃. The commercial filter inlet for gases and AEROsols (FIGAERO) applied to PM2.5 detection has key bottleneck problems, such as insufficient heating power and poor airtightness. In this work, a rapid thermal desorption device was developed, coupled to a home-made photochemical ionization mass spectrometer (CIMS), with a detection time within 5 min. The self-designed thermal desorption device applies high-power mica sheets for heating, which can stably maintain a heating temperature of 300 ℃ to ensure the complete desorption of polycyclic aromatic hydrocarbons (PAHs) in particulate matter. Using this device, three common PAHs, naphthalene, acenaphthylene, and fluorene in PM2.5 were rapidly analyzed. The molecular ion peak of PAHs was used as the characteristic peak, with the linear range of 2-2 000 ng and the detection limit of 0.021, 0.36 and 0.68 ng, respectively. Most importantly, the device was used to analyze the components of actual particulate samples collected from car park and smoking room. Within m/z 0-300, the number of peaks was determined using a threshold of a signal-to-noise ratio of >3, with the background signal of the blank film considered as noise. Using the self-designed device, the characteristic peak counts for particulate samples of car park and smoking gas samples were 182, 202, respectively. In contrast, the characteristic peak count for particulate samples of car park using FIGAERO was only 23, and no characteristic peak was observed for smoking gas particle samples. Therefore, compared with FIGAERO, the self-designed thermal desorption device coupled with photochemical ionization mass spectrometry has a highly significant advantage and can achieve quantitative detection of trace PAHs in particulate matter. This device demonstrates significant potential and broad development prospects in the field of particulate matter analysis.