Abstract: Objective To study the knowledge,attitude and practice(KAP)of obesity among prmiary school students,and to provide basis for obesity prevention in the students.Methods Astratified cluster random sampling was conducted among 6 prmiary schools,grade 2-5 in Ji'nan city.Medical examination and a questionnaire survey were con ducted in 1915 studentsse lected.EpiData 3.02 and SPSS 16.0 were used in the data analysis.Results The correctanswer rate of 11 questions about nutrition knowledge was more than 80%,and the KAP of the female pupils was better than that of the male pupils(P < 0.05).There were 15 58(87.2%)pupils eating breakfast every day,942(49.19%)drinking milk or yoghourt every day,and 994(51.9%)eating western-sytle fast food in the previous month.The main sources of obesity knowledge were new spaper,magazine,book,and television broadcasting.Conclusion The pupils are good at the knowledge of nutrition but the knowledge is not comprehen sive and systemic.And the unhealthy diatary behavior is common in the pupils.