Abstract: In order to provide a theoretical basis for the bamboo softening and flattening, the storage modulus, loss modulus and glass transition temperature(Tg)of moso bamboo were investigated by dynamic mechanical analysis(DMTA)at various initial moisture contents(MC), radial positions, ages and heights. Results showed that the storage modulus decreased with the temperature increasing. The loss modulus increased firstly and then decreased, but when temperature reached a certain extent, loss modulus increased and then decreased again. The moisture content had a great effect on storage modulus and loss modulus, but both moduli decreased with the MC increasing. The storage modulus and loss modulus increased from inner to outer layer in the radial direction and decreased with the height increasing. Besides, the age had a positive but tiny influence on both storage modulus and loss modulus. As MC increasing, Tg decreased from 217-223 ℃at absolute dry to 113-134 ℃ at MC above 15%. The Tg of outer, median and inner layers of bamboo in the radial direction showed slight differences and they were 123-135 ℃ for bamboo at 30% MC, while they were not affected significantly by the age or height,ranginge from 120℃ to123 ℃ and 123℃ to126 ℃ for different ages and heights, respectively. This study showed that the increase of ambient temperature and MC of bamboo could improve the plasticity of bamboo. This provides the wider choice of bamboo timber at its ages and heights, too.