Objective  To evaluate the clinical therapeutic efficacy and safety  of sibutramine to simple obesity and compare the effects of sibutramine and placebo on resting metabolic rate.Method  By means of random,double  blind,placebo  parallel control and multicentral trial,58 simple obesity volunteers were observed for 24 weeks.Results  1.Compared with placebo,sibutramine can reduce parameters of simple obesity,including body weight,body weight index,waist and hip size,significantly(  P  <0.000?1).Whereas,there were no significant differences to be observed in the placebo group.2.In each group there were no significant differences to be observed in blood routine and biochemistry parameters before and  after the clinical trial.3.Sibutramine increased diastolic pressure significantly in the trial of 4,8 and 12 weeks,but the variation of the diastolic pressure still in the normal range,whereas there was no significant variation of diastolic pressure to be observed in placebo group.4.There were no significant differences of the variation of resting metabolic rate between sibutramine and placebo group during the clinical trial.Conclusion  Sibutramine,compared with placebo,can significantly reduce bodyweight and increase diastolic pressure,whereas no significant variations of resting metabolic rate to be observed.