To monitor plant disease which caused by spores, it is needed to obtain the spores image exterior outline characteristic, prepares for spores type analysis and automatic counting. This paper uses computer assistance digital image processing, realized image pretreatment, determined the threshold value reasonably, and transformed the gray image to binary image. Images was captured by CCD and input into computer for process. A kind of gray images research method has been proposed. In order to remove low frequency components, the input gray image is preprocessed by edge enhancement using the Median filter and canny edge algorithm. In this foundation using the imagery processing technology carries on morphology analyses, feature extraction and track. Its goal is obtains the spore image exterior outline characteristic, completes the spores type analysis, counting and distinguish.