Abstract: A system and method for analyzing the size distribution and chemical composition of neutral clusters below 3 nm, which achieves efficient sampling based on a core sampling method. The system utilizes the high charging efficiency of the unipolar charging device to charge the nanoparticles and efficiently transport them to the inlet of the nanoparticle electrical mobility size classification device. Through a specialized aerodynamic design, the nanoparticles pass through the electric field between the electrode plates and are efficiently transmitted to both the particle number concentration detector and the chemical composition detector, demonstrating excellent application prospects.