Abstract: Based on floating point DSP (TMS320C6748) processor, we design a dark field image processing system in real time, with discussing the theory and the design method and providing the implementation of the system. On this basis, we make experiments of dark field images acquisition and analysis on gold nanospheres. Stepper motor controls the optical grating rotation of dark field, matching the successive acquisition of dark-field images; Simultaneously, CMOS camera acquires the images, which to be processed by DSP, and then we get the scattering spectra of sample. The experiments show that scattering spectra of gold nanospheres consists with the actual spectral properties of gold nanospheres and the functions and properties of the system reach the expectations.The image processing system accomplishes the real-time processing feature of dark field image, which has great application value on detection of early Tumor, heavy metals, chemical and biological and other fields.