Abstract: A field survey for submerged macrophyte of Lake Erhai was carried out in April 1998. The survey initially revealed the dominant species, the community types and their distribution, and the biomass in the spring of the submerged macrophyte of Lake Erhai. The dynamic change characteristics of submerged macrophyte were analyzed based on relevant historical data. These characteristics included decrease of submerged macrophyte species, simplification of community, changing of the dominant species to pollutant-resistant species of P. maackianus A. Benn. and deterioration of plant resources of the whole lake. Eutrophication and pen-fishing, as two main factors affecting the dynamic change of submerged macrophyte in Lake Erhai, were finally discussed.