Abstract: The microfibril angle of moso bamboo aged from 1.5 to 10.5 years was measured and analyzed by Xray diffraction estimation. Temporal and spatial variation patterns were studied in this paper. The results showed that the radial variation of the microfibril angle of secondary cell wall within ages took irregular tendency with the distance ranged from bark to pith. The average, maximum and minimum of radial microfibril angle separately was 9.4°, 12.05° and 7.61°，the difference is less than 4.44° . The microfibril angle increased from 0.5 to 1.5 year, following decreased, then increased reached 6.5 year, but a large value present in 10.5 year. There was significant difference between age of bamboo and microfibril angle. Longitudinal variations of MFA decreased with increased bamboo height, with 9.32°，9.39°and 9.50° separately in the top, middle and base of bamboo.