In order to detect and analyze the number and size of particulate matter in liquid media, the characterization of standard spherical particles were investigated by the method of light-blockage related to geometric optics and Mie scattering theory, while the method of angle scattering and the image method were used to verify the consistency of the measurement. A system was established that could be available simultaneously for the three methods. To perform a calibration, the amplitudes of obtained light-blockage signal for standard particles with six different sizes were statistically averaged and fitted, which consequently provided a fitting formula to determine the measurement results of other particles. The results for two standard particles and a mixed particle system showed that the median diameters for particles with nominal value of both 15.0 μm and 63.6 μm yielded a deviation less than 2%, and the mixed particles were also well identified in size.