Abstract: It is extremely important to auto-generation examination papers for high school,with the purpose of making examination normative and scientific. The average scores of students can be controlled by average difficulty level of the examination paper. However, how to quantify various difficulty levels of test questions is a key step. Currently, a common strategy is to adopt normal distribution to specify those numbers. After discretizing the normal distribution function based on the difficulty factor, the probability distributions of various difficulty levels were obtained according to symmetrical integral and a proportion error complementary method was adopted to reduce errors. According to the analysis results in the auto-generation examination papers, the standard deviation of 0. 2 is more suitable. In last, the computed numbers of various difficulty levels of test questions arc listed in various total questions. The result shows that the control method that use discrete error complementary strategy can control the ctuantity of various difficulty levels of test questions well and enable the strategy of auto-generation examination papers to be effective.

Key words: Auto-generation examination papers, Discretization, Error complementary method, Difficulty distribution,Normal distribution