<p>Accurate measurements of aerosol optical and chemical properties are paramount for evaluating atmospheric radiative forcing and comprehending the processes involved in the formation, growth, and evolution of new particles. This review focuses on the direct measurement techniques of the optical and chemical properties of aerosols over the past 20 years. Here, optical properties involve the absorption, scattering, extinction and single scattering albedo. The merits, demerits and limitations of each technique in both laboratory and field applications are summarized. Furthermore, we also propose future directions for technological improvement and instrument development of our comments in this field. Additionally, the impacts of aerosols on climate and environment, as well as health risk associated with exposure to high concentrations of ultrafine particles, are briefly elucidated. Enhancing existing techniques to improve their accuracy and adaptability to various environmental conditions is recommended. Concurrently, there is a need to develop innovative technologies capable of simultaneously measuring multiple parameters across diverse spectral and size ranges. These direct measurement techniques serve as a valuable reference for advancing future research and instrumentation development in the field of aerosol science.</p>