Erhai Lake is the seventh largest freshwater lake in China where has been encountered with water pollution by the algae. One of important indicator of the water quality is the density of algae in the water, and the growth rate of algae is eutrophication. A novel method is proposed to discover the association of algae with physicochemical variables related to the algae growth in Erhai Lake, by integrating Maximal information coefficient(MIC) and association rules. To measure the correlation between variables, a new aspect on association rules with non-occurring domain is purposed, which decreases one item in antecedent. The correlation results present significantly in the density levels of algae, which is beneficial to control the level of physicochemical in the water for preventing the increasing number of algae.