The work aims to take loofah sponge as the raw material,combine alkaline boiling with sodium hypochlorite oxidation tostudy the effects of different extraction methods on the fiber structure of loofah sponge and fiber yield. The products were characterized by SEM, FTIR, TGA and XRD to investigate changes in surface topography,impurity removal, chemical structure, thermal stability, etc. of loofah sponge fiber. The results showed that the hemicellulose might be removed from the raw material by alkali boiling to yield micron-sized fiber, and lignin can be removed by oxidation treatment. No obvious change was found in the thermal stability of the fiber at different stages, but the crystalline content increased. The yield of loofah microfiber was related to ratio of alkali to sodium hypochlorite in the oxidation solution, oxidation temperature and availability of ultrasonic. A higher temperature promoted the fiber yield. Ultrasonic assisted extraction might significantly improve the yield and shorten the extraction time. Loofah micro-fiber can be effectively extracted (a maximum yield of 35.7%)by method of alkali boiling and sodium hypochlorite oxidation with the aid of ultrasound.