The concentration and composition of bioaerosols in the ambient air are closely related to human health. Obtaining real-time information on the types of bioaerosols is a challenge for bioaerosol monitoring today. Aiming to realize automatic detection with low cost and low false alarm rate, we describe a bioaerosol detection system with dual fluorescence receiving channels excited by ultraviolet light. The system uses 280-nm UV-LED to excite the intrinsic fluorescence of biological particles, and according to the emission bands of NADH, riboflavin, and tryptophan, it is divided into two fluorescence bands: 330 to 420 nm and 420 to 650 nm. A series of experiments were conducted to evaluate the detection capability of the system. The results showed that the system has good consistency with the culture method in concentration detection and has good reproducibility. We detected multiple types of aerosol particles. By comparing the fluorescence intensity of the two bands, the system can not only distinguish between fluorescent and nonfluorescent particles but also preclassify the biological particles into four categories: proteinaceous substances and microorganisms with tryptophan as the main component, dust particles in the air, plant cells and debris, and cigarette burning smoke.