Abstract: In order to carrying on the intelligent disease prevention and cure for glasshouse plants, this paper researched two kinds of familiar cucumber diseases in the method of picture processing. Compared several kinds of hue system using hue H as the color characteristic parameter, and distinguished between normal leaf and diseased leaf according to hue histogram statistic parameters and chroma histogram of section value. Studied the chroma distribution of normal and diseased leaves in different hue extent. The results showed that(48～50) and (45～47) were the best extent to distinct normal and diseased leaves. This paper provides important characteristic parameters for the pattern identified.