AbstractWater hyacinth (Eichhornia crassipes) is an invasive floating plant that has caused many environmental problems in Asia. Efficiently removing and utilizing this biomass has become an urgent issue. In this work, the composition of water hyacinth biomass (WHB) was analyzed with the Van Soest method. The combined cellulose and hemicellulose content reached 58.6%, and the lignin content was very low compared with other biomass. An efficient alkali pretreatment technology for WHB was developed, and the enzymatic hydrolysis of WHB to reducing sugars was investigated. With favorable hydrolysis conditions for the alkali-pretreated WHB, the cellulose conversion rate reached almost 100%. Structural changes resulting from WHB pretreatment and hydrolysis were analyzed by Fourier-transform infrared spectrometry and scanning electron microscopy. This work demonstrates that WHB is an alternative cellulose source for bioenergy production.