Abstract: Particle testing is widely involved in scientific research and industry.The frequently used examination method for particle size and distribution is laser particle size distribution test method，which owns especial advantages such as high precision,high speed, good repeatability and wide measuring range.Its a common trend that using CCD as the sensor of laser particle analyzer can improve the intensity resolution,because CCD sensor has the merits of high sensibility,high resolution, low noise and great dynamic range.For enhancing the measuring accuracy, using image processing technique to design detector was presented based on the study of CCD sensor technology，and a laser particle size analysing system was realized based on Mie scattering theory.The experimental results indicate that using the CCD sensor to capture the light scattering spectra of image and then using image processing techniques to design photodetector enhance the measuring precision and reduce the repetition error effectively.