Using the Chernin multipass cell for measurement of aerosol extinction coefficient is reported. Within 38.4 m absorption optical path can realize detection sensitivity to 18 Mm - 1(5 s integrating time,and 30 times average). Combining a laboratory aerosol generation system, the extinction coefficients of 250 nm diameter monodispersed ammonium sulfate aerosol are measured under different particle concentrations. Three cross sections of 1.410 × 10-9，3.727 × 10-10，2.948 × 10-10 cm2 for ammonium sulfate aerosols at 300, 532, 532 nm is obtained, respectively. Error analysis carried out on the experimental results shows that this system can be used in the quantitative study of aerosol optical properties.