Taking Phragmites australis （Cav.） Trin. ex Steud. from wetlands in Heyang County and Fuping County of Weinan City， Nanzheng District of Hanzhong City， and Weibin District of Baoji City of Shaanxi Province as research objects， caloric value （including gross caloric value and ash free caloric value） and ash content in root， stem， leaf， and leaf sheath of P. australis during vigorous growth period （from Jun. to Aug.） were compared. Regarding the averages of three indexes of different organs of P. australis from each wetland during the experimental period， gross caloric value and ash free caloric value in each organ of P. australis from the four test wetlands are the highest in leaf and the lowest in leaf sheath， while ash content is the highest in leaf sheath and the lowest in stem or root. It is suggested that ash has some effect on caloric value of different organs of P. australis from the four test wetlands， after removing ash， the caloric value of each organ of P. australis increases in different degrees.