Objective: To develop the Adolescent Mental Health Literacy Assessment Questionnaire (AMHLAQ), and to evaluate its reliability and validity among undergraduates. Methods: On the basis of the definition of mental health literacy (MHL) and the Knowledge, Attitudes and Practices (KAP) theory, this study constructed a total of 36 items consisting of four dimensions, and scores were measured according to a five point Likert type scale. Using a cluster sampling method, a questionnaire survey was conducted among 3 826 freshmen and sophomore students from two medical schools in Anhui Province. The items were screened by performing t tests, Pearson s correlation coefficient analysis and factor analysis. The reliability and validity of the questionnaire were evaluated using indicators including homogeneity reliability, the split half reliability coefficient, and construct validity. Results: Factor analysis revealed that the AMHLAQ consisted of 22 questions grouped into four domains. The variance cumulative contribution rate was 62.213%. The reliability result showed that the Cronbach s alpha coefficient of the total questionnaire was 0.897, the split half reliability was 0.800, the Cronbach s coefficient of each dimension was 0.796 to 0.885, the split half reliability of each dimension was 0.725 to 0.846, and the indicators had a high level of reliability. Confirmatory factor analysis showed that the model fit was good ( χ 2/df =19.319, P <0.01; RMSEA=0.069). Conclusion AMHLAQ is consistent with the evaluation standard of psychometrics, has good reliability and validity, and can be used to estimate the level of MHL among undergraduates.