Abstract: The graduate record examination is the foundation and guarantee of students' quality. In this paper, mathematical statistics is used to analyze the grades of basic and major courses from 2004 to 2006 in China Agriculture University, so as to detect the reasonability of the test papers, according to which scientific adjustment advices are proposed. Through comparison of entrance grades and after-enrollment comprehensive quality assessment, the impact factors influencing the overall quality is estimated quantitatively. Finally, scientific enrollment suggestions are proposed.