Abstract: ObjectiveIn order to provide theoretical basis for eutrophic water purification and duckweed biomass uti-lization in the future, the effects of duckweed species diversity on eutrophic water purification and duckweed biomass accu-mulation were investigated. MethodThree duckweed species, Lemna aequinoctialis LC33, Landoltia punctata LC06 and Spirodela polyrhiza LC15, were cultured both individually and in mixture to measure their removal rates of nitrogen and phosphorus, and to analyze biomass content of mixed combinations. ResultCombination of L. punctata LC06 and S. polyrhiza LC15 showed the highest removal efficiency of nitrate nitrogen(NO3--N), total nitrogen(TN) and total phosphorus (TP), reaching 97.05%、95.00%and 97.64%respectively;while combination of L. aequinoctialis LC33, L. punctata LC06 and S. polyrhiza LC15 showed the highest removal efficiency of ammonia nitrogen(NH4+-N), reaching 98.17%. Moreover, compared with other groups, polyculture of L. aequinoctialis LC33 and L. punctata LC06, polyculture of L. punctata LC06 and S. polyrhiza LC15 exhibited higher biomass growth rate; polyculture of L. aequinoctialis LC33 and L. punctata LC06 accumulated more starch; polyculture of L. punctata LC06 and S. polyrhiza LC15 accumulated more crude protein. Con-clusionAppropriate combination of duckweed species can enhance purifying effects of eutrophic water, and promote biomass accumulation.