Abstract: As one of the primary sources of atmospheric particulate matter,the emissions of particulate matter( PM) from coal-fired power plants have been widely concerned. It is of great significance to realize the accurate on-line monitoring of PM mass concentration. As a commonly used on-line measurement method for PM concentration,the light extinction method is likely to cause a large deviation due to the influence of particle characteristics. To explore the effect of particle shape on the mass concentration measurement,the light extinction test rig was set up,and the test system was calibrated by spherical silica particles. The calibration results show that the mass concentration of spherical silica particles is highly linearly related to the extinction ratio,the correlation coefficient R2 is greater than 0.99,and the deviation between the measured concentration and the actual concentration is only 1.8%. Furthermore,three kinds of non-spherical( prismatic,irregular and flaky) silica particles were tested with two wavelengths at 633 nm and 532 nm respectively. The results show that the mass concentration of the three kinds of particles is highly correlated with the extinction ratio,and R2 is higher than 0.99; the deviation of the measured value and the actual value of the three shapes of particle mass concentration varies with the shape of the particles and the incident wavelength. When the incident wavelength is 633 nm,the measured deviations of the mass concentration of irregular,prismatic and flake particles from the actual value are 16.1%,27.4% and 36.6%,respectively. When the incident wavelength is 532 nm,the measurement deviations of the mass concentrations of three kinds of particle are 4.8%,11.4% and 17.4% respectively; under the condition of the same particle shape,the measurement deviation at the incident wavelength of 532 nm is significantly smaller. The measurement deviation caused by the change of particle shape can be reduced by the selection of the wavelength.