Abstract: Fuzzy mathematics is a brandnew subject of mathematics. Additionally, it is a great breakthrough from the science of computer to the mechanism of physical science for human being. The grid is regarded as the hottest topic in the research of information and technology area for several decades. The paper uses fuzzy mathematics as a tool to evaluate the trust model and the grade of service quality, which makes the assess of users trust values become more accurate, flexible and reliable. Fuzzy language variable is a quantitative, descriptive model which can describe the fuzzy character of trust and show the characteristic of itselfintuition and concision. It also can depict the dynamic quality of the grid and promote the development trust model of the grid in the theory.

Key words: grid, grid trust model, fuzzy mathematics