The advantages and shortcomings of the classical grey relational decision-making method are analyzed based on grey relational decision theory. The polygon area between adjacent points in the curve is considered to measure the proximity of the curve on the distance and the similarity of the geometry shape. And the polygon area between adjacent points in the selected project and ideal project is regarded as the relational coefficient to construct the grey relational formula. In order to settle the problems of insufficient information using and inconsistent changes, the correlation between the selected project and the ideal project needs to be considered, and the model of grey incidence relative closeness is constructed. An example is given to verify the rationality of the grey relational decision model and the effectiveness of the proposed algorithm.