Abstract: In order to ensure the obvious improvement of the water body and tourism landscape in Caohai of Dianchi Lake during 1999 International Horticultural Exposition, emergency measures for the removal of blue algae in the sensitive water area of the lake were implemented. In view of the characteristic of different pollution, all kinds of measures including medicament purification, mechanical algae removal, water separation and landscaping of water hyacinth were taken. With the cooperation of water resource regulation measure, comprehensive pollution treatment engineering and administrative and management measures, the purpose of ensuring the obvious improvement of sensitive water area in Caohai and north of Waihai is expected to be achieved.