Objective To compile an applicable inventory of academic diligence for middle school students. Method By means of literature analysis and in-deep interview with teachers, an academic diligence inventory was constructed and used for 393 high school students. Such methods as correlation analysis, exploratory factor analysis and reliability analysis were analyzed by SPSS11. 0 for windows XP. Results ① Five principal components of academic diligence were selected, which could be called target monitoring, time investment, task commitment, persistence and concentration. ②Internal consistency reliability and split-half reliability of total scale are 0. 9126 and 0. 9003. Reliability of each subscale are above 0. 7615. Correlation coefficient between subscales and total scale ranged from 0. 672 to 0. 820. That of among subscales ranged from 0. 248 to 0. 521. Conclusion Reliability and validity of the inventory of academic diligence for middle school students are both satisfactory enough to meet psychometric indexes.