The effects of three physical pretreatment methods (water bath, ultrasound and microwave) on the cellulose recovery of water hyacinth were investigated in this study. Before treatment, cellulose and hemicellulose content of dried water hyacinth sample was 36.04%. After treating by ultrasound (70oC for 1 h) at a ratio of deionized water (DIW) (mL) to dried sample (g) of 10:1, cellulose and hemicellulose content in the treated sample was 57.70.65 %. The highest yield of cellulose and hemicellulose (58.190.59%) obtained by water bath treament at 100oC for 1 h whereas the cellulose and hemicellulose yield was 60.420.07% attained by microwave pretreatment (350W, 10 min at a ratio of DIW (mL) to dried sample (g) of 10:1). Therefore, among three pretreatment methods, microwave assisted DIW pretreatment presented the best efficiency on cellulose recovery. The outcome showed that microwave assisted DIW pretreated water hyacinth is a promising raw material for bioethanol production. The effects of these treatments on the composition and structure of water hyacinth were studied by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM).