Monthly phytolith-occluded organic carbon (PhytOC) content in living leaves and litterfall of Moso bamboo (Phyllostachys edulis) were measured for a year. The PhytOC sequestration rate in living leaves of different months were compared with that in annual litterfall to determine the optimum sampling time of living leaves for estimating PhytOC sequestration rate of Moso bamboo. The contents of phytoliths and PhytOC in living leaves of Moso bamboos were 23.45-101.07 g·kg and 0.73-1.98 g·kg, respectively, with significant difference among different months. The monthly PhytOC sequestration rates of living leaves of Moso bamboo in different months ranged from 0.75 to 7.68 kg·hm·a. The maximum and minimum rates of the PhytOC sequestration occurred in December and April respectively, with significant difference between them. There was no difference between the PhytOC sequestration rate in living leaves of Moso bamboos in February or December and that of litterfall in the whole year. Therefore, February or December should be the optimal month of sampling living leaves for estimating the PhytOC sequestration rate of Moso bamboo stands.