Abstract: This poper reports the followins results of study on infection cycle of Moso bamboo foot rot caused by Arthrinium phaeospermam: (1) The Pathogen is over winter on (or in) the diseased or killed culms. stumps. fallen leaves and soil with mycelia or spores. It is the source of primary infection; (2) The wind and water splash are the most important means of dispersing the spores; (3) The invadins channels of the pethogen are believed to take place through the tender epidermis unwounded; (4)The results of observation and isolation indicate that infection mechanism is the toxin excreted by pethogen; (5) No secondary infection has been founded.