In response to the ecological problem of high pH and blue-green algae concentration in Dianchi Lake, using automatic monitoring weekly report data, the pH value and its change trend of the most representative Guanyinshan Section in Dianchi Lake from 2004 to 2018 were analyzed. It was found that during this period, the rate of pH exceeding the standard was generally high, with an extreme pH value as high as 10.38. Combined with relevant literature, the restrictive effect of high pH values on submerged plants, zooplankton, and fish that play an important role in ecological restoration of Dianchi Lake were analyzed, as well as their potential promoting influence on Microcystis aeruginosa and Anabaena flos-aquae. In order to better promote the effectiveness of ecological governance and ecological restoration process in Dianchi Lake, it is recommended to strengthen the research on the mechanism of high pH formation in Dianchi Lake, strengthen the alleviation effect of water diversion projects from rivers entering the lake and Niulan River on high pH in Dianchi Lake, and strengthen the research and engineering construction of endogenous pollution control of pH in Dianchi Lake.