Abstract: The distribution of acid phosphatase during fiber development in the culm of Phyllostachys edulis (Cart.) H. De Lehaie was studied by using the lead precipitation method. Acid phosphatase (APase) was mainly localized on the plasmalemma and nuclear chromatin at the stage of fiber initial formation. With the primary wall formation, the enzymatic activity in the cells was examined on the plasmalemma, tonoplast and nuclear chromatin. The enzyme activity on the nuclear chromatin would condensely be accumulated at the later stage of fiber primary wall formation. As fiber secondary wall formed, APase was deposited on the plasmalemma, the disintegrated cytoplasm, mitochondrion and tonoplast and the agglutinated chromatin. With the continual thickening of the secondary wall, APase activity on the plasmalemma, plasmodesmata, plasmalemma invagination and transfer vesicles and agglutinated chromatin of fiber were persistent for many years. These findings indicated that the APase condensely accumulated on the nuclear chromatin was closely related to the occurrence of fiber programmed cell death (PCD), and APase had functions in the whole formation of primary and secondary wall, and the disintegration of protoplast during PCD, and the persistent APase was correlated to the long-lived characteristic of fiber.