As technology develops, digital image processing technology has become a new method for studying particle property and a necessary means for particle analysis. This method helps researchers to gain deeper understanding of microstructure and property of powder particles. In the paper, samples are composed with two kinds of cement powders: cement clinker and slag powder, which have different characteristics and shapes. The paper analyzed the characteristics of different ingredient and mixing evenness degree of cement sample by using the technology of SEM backscattered electron image and the theoretical calculation model. On the basis of experimental analysis, a new method was proposed to quantitatively analyze evenness degree for the cement mixture basing on image processing, which adopts the advanced microscopic analysis technology. This new method is tested by experiments, and results prove that this method is effective and is superior to other methods.