Pu-erh Tea is a kind of famous tea in Yunnan known for its long history and effect of health care. Nowadays with the consumption of Pu-erh Tea increasing quickly, and people pay more and more attention on food safety,, the consumers are strict with sanitation and quality of Pu-erh Tea. This study aims at analysing the biological, physical and chemical harmfulness of Pu-erh Tea and its origin, start with the investigation of microorganisms, foreign matters and heavy metal pollution in the processing period. ...