Aerosol diffusion dryer is an instrument that removes water from aerosol particles. Moist aerosol flows through stainless steel semi-transparent tube, water in aerosol is dried and removed by diffusion without direct contact with molecular sieve desiccant. Due to no direct contact with silica gel desiccant, particle loss is very small. It is usually connected with aerosol generator, which dries atomized aerosol and produces solid condensation nucleus or monodisperse PSL spheres.