In this study, we developed a particle sampler for aerosol suspensions (PSAS) that collects ambient PM2.5 directly as liquid suspensions. The PSAS, which operates at a sampling rate of 50 L min–1, first pre-selects fine particles with a custom-designed PM2.5 inlet and then enlarges them into 2–5 µm droplets via condensational growth with a saturation-condensation unit. Subsequently, the enlarged droplets are sequentially collected in our novel collection impactor as liquid suspensions. Laboratory evaluations indicate good collection efficiencies for the PSAS with both polydisperse and monodisperse fine particles, with 85% of the particles being effectively preserved in the collected suspensions. Field evaluations suggest good agreement between the PSAS suspensions and parallel filter samples for the analyzed chemical components (water-soluble Fe(II) and Cr(VI)) in the ambient PM2.5. Thus, the PSAS is suitable for long-term particle collection and can be used to facilitate the online chemical and toxicological analysis of ambient PM2.5.