Abstract:The effects of environmental factors on stream macroalgae were investigated. Data were collected from July 2009 to April 2010 from Xin’an Spring, Shanxi Province, north China. The environmental variables consisted of water temperature, pH, specific conductance, dissolved oxygen, surface current velocity, maximum depth and width. Fortytwo species of stream macroalgae were identified in this spring. The correlation between these seven environmental factors and the number of stream macroalgal species were determined using grey correlation analysis. The results showed that water temperature and current velocity were the key factors affecting the number of stream macroalgae. This result was consistent with previous studies. Therefore, it indicated that the grey correlation analysis can be used in the study of algal ecological environment.