Objective　To explore the new model of teaching assessment and evaluation of sanitary microbiology studied by students majoring in preventive medicine. Methods　Combination of formative assessment and summative assessment was applied in the teaching for students in under-graduate preventive medicine class in Grade 2007-2010. To get better effect， method was improved constantly. Pearson correlation analysis was used to students' formative assessment and summative as-sessment， and comprehensive evaluation achievement（the first two added）. Moreover， the effects were assessed by teachers' self-evaluation and their exchanging ideas with students. Results　Ranging from 10.06 to 12.22， the standard deviations of four grades' summative assessment results were the biggest number， so the summative assessment was more effective. Students' formative assessment， summative assessment， and comprehensive assessment for this course were positively correlated（P<0.01） for suc-cessive four years. Teachers and students approved of the new mode. Conclusion　The effective com-bination of formative assessment and summative assessment was helpful for student to develop and assess learning ability and overall qualities， and for teachers to improve teaching level.