Luffa fiber, a natural polymer material abundant all over the world, is made up of cellulose,hemicellulose and lignin.It has a special adsorption property due to the amphiphilic chemical structure and porous vascular bundle.In this paper, luffa was pretreated then esterified with acetic anhydride.FTIR was used to investigate the degree of esterification, which showed that esterified by microwave radiation was much better than by oil bath and the esterified degree increased with time.XRD was adopted to study its crystal form and showed that combined treatment with microwave / ethanol / 30% NaOH would result in a transition of luffa from cellulose Ⅰto Ⅱ, which retained cellulose Ⅱ after esterification.