Bessel beam optical tweezer is built for particle measurement. An axicon is used to generate Bessel beam. The trapped single aerosol particle is stably levitated by optical force exerted by Bessel beam and drag force exerted by the counter gas flow. In combination with light signal scattered by the levitated aerosol particle, the diameter and the refractive index can be measured. Physicochemical properties of aerosol, such as hygroscopicity, volatility, and the refractive index, could be studied under different environmental conditions with this system.