Abstract: Based on the investigation on bamboo mildew-rotting in Zhejiang,Fujian,Hunan and Jiangxi provinces which are China’s dominant bamboo timber production area,the type of bamboo mildew-rotting and the relation between its occurrence and environmental condition were studied and analyzed.The mildew and rot can be divided into 4 types,i.e.fragmentary distribution,even distribution,covered by hyphae and rot.Each type correlates with certain environmental condition.It is considered that the different humidity,temperature lead to the variance of mildew-rotting type.Some suggestions such as improving environment,controlling humidity and temperature were put forward in order to prevent bamboo products from being mildewed and rotted.