Abstract: Moso bamboo (Phyllostachys edulis), a member of Bambusoideae (Bambusoideae), Gramineae (Poaceae), is one of the most important economic bamboo species in China and in the world. We aimed to estimate the genome size of moso bamboo by flow cytometry, using rice (Oryza sativa) as an internal reference. After comparing the peak values of the fluorescence intensity of 24 bamboo and rice samples, we calculated the genome size of moso bamboo to be about 2075.025± 13.08 Mb, or 2 C DNA about 4.24 pg (1 pg DNA = 0.978×109 bp). The results of this study will help in future research of the moso bamboo genome.