In this paper, we establish a trustworthy attribute model, consisting of the critical attributes taken out from the attribute set referring to definitions associated with trustworthiness and of non-critical attributes selected by the users according to their requirements. We define a program as a collection of program elements and program units, and build inventories for them. These inventories include not only properties and functions that program elements and program units should carry if they are trustworthy, but also the corresponding relation between them and the trustworthy attributes. Based on these inventories, we present a quantitative relation model between trustworthy attributes.