Abstract: Objective To investigate the prevalence of obesity and its effect on cardiopulmonary fuction among the primary school students in Suzhou city for prevention and control of simple obesity.Methods Totally 6 299 students from 6 primary schools were investigated and 60 students with simple obesity(30 males,30 females) were tested for pulmonary ventilation function and electrocardiogram.Results The total obesity rate of the students was 7.6%(8.7% in male,6.4% in female).The total overweight rate was 10.4%(11.6% in male,8.9% in female).Compared with the students with normal body weight,the obesity students had obviously lower maximum voluntory ventilation(MVV),forced expiratory volume in 1 second(FEV₁),maximal expiratory flowat 50%(MEF₅₀),and peak expiratory flowrate(PEFR) and higher functional residual capasity(FRC).The QT despersion(QTd) and QT despersion corrected of the obesity students were significantly longer than those of the students with normal body weight(42.11±10.57 vs 36.77±9.63,P < 0.05; 50.29±11.69 vs 42.43±10.11,P < 0.01).Conclusion Simple obesity induces the decrease of pulmonary ventilation function and abnormal electrocardiogram in primary school students.