The lifespan of botanical fine roots is crucial to fine root turnover, plays an important role in the carbon and nutrient cycle of terrestrial ecosystem. However, so far there is no sufficient data and research that has been directly observed or conducted on the lifespan of bamboo roots, particularly in the characteristics of Phyllostachys glauca culm and rhizome roots. In this study, Rhizoboxes were used to study the dynamics of culm and rhizome root of Phyllostachys glauca. The results showed that: (1) There were no significant differences on lifespans between culm and rhizome roots. Root lifespans increased as the root order rose. The lifespans of first-order roots were significantly lower than those of second-order roots, and the lifespans of second-order roots were lower than those of third-order roots. (2) The birth and death of culm and rhizome roots have different seasonal patterns. The birth of rhizome roots was concentrated in July, August, and September. Rhizome roots birth peaked in July and death peaked in spring (from March to May). For the culm roots, there was no single peak in the birth but small peaks in March, July, and November. Culm roots’ death peaked in summer (from June to August). (3) The relations between the lifespan and birth date of culm and rhizome roots differed. Culm roots born in summer had the longest median lifespans while those born in spring had the shortest. Rhizome roots born in spring had the longest median lifespans while those born in winter (from December to February) had the shortest. Our findings indicated that culm and rhizome roots had different growth patterns, and their lifespan is closely related to root order and birth date. This study could provide a theoretical basis for bamboo forest production and management.