X-ray fluorescence (XRF) analysis of single aerosol particles is a useful tool for identifying origins of aerosol particles. A micro-XRF spectrometer based on a monolithic capillary X-ray lens (MCXRL) and laboratory X-ray source is designed in order to carry out the XRF analysis of single aerosol particles. The order of magnitude of the gain of power density of the MCXRL is 103 at the focal spot, and the focal spot size of the MCXRL is about 30 μm. The minimum detection limit (MDL) of this spectrometer is 0.7 pg for the Fe-Kα. The XRF spectrum of a single aerosol particle with a diameter of 9 μm is obtained within 180 s when the working voltage and current of a Mo rotating anode X-ray generator are 30 kV and 50 mA, respectively. The experimental results show that the designed spectrometer has potential applications in the analysis of single aerosol particles.