The traditional description method of project risk is analyzed and the good and bad points of these methods are discussed. Multi-dimensional structure, a description method of project risk is put forward. A project risk is discribed five aspects of risk event such as occurrence probability, lost, predictability, manipulability, the degree of information asymmetries and so on. The function of the risk degree and measurement function of project risk are established. An application case study is provided. Multi-dimensional description and measurement of project risk which can reflect comprehensively the real appearance of project risk, and it is advantageous for us to know and gras Pthe rule of project risk.