Objective　To explore the method of building the formative assessment (FA) system in diagnostics teaching and investigate its implementation effect. Methods　We planned and formulated the formative assessment system in diagnostics teaching of undergraduate curriculum. The correlation between the scores of the formative assessment and final exam were analyzed. A questionnaire survey on students' attitudes towards FA and an interview on teachers' perspectives were conducted. SPSS 17.0 was used for statistical analysis. Linear correlation analysis was used to compare the final exam scores with formative assessment scores

and Wilcoxon rank sum test was used to compare the scores of questionnaire items. Results　The scores of FA were significantly positive related to the scores of final exam (r = 0.559

P < 0.001). The questionnaire analysis showed that students significantly valued the formative assessment superior to the summative assessment (Z = -8.632

P<0.001). It was generally approved of the promotion of FA in students' self-direct learning and self-supervision and the advances in acquirement of knowledge and skills. Conclusion　It is feasible of carrying FA in diagnostics teaching which could provide better learning outcome and might have an extensive prospect of application.