Abstract: Objective To explore the effects on the workers exposed to low concentration.Methods Thirty four workers exposed to low concentraction of TDI with thirty two workers of control group are compared by physical examination.Results The morbidity of the symptoms of diziness,hidradenitis of hands and feet,fatigue,sore-throat,skin rash in the exposed group were higher significantly than in the control workers(P<0.05).FVC,FEV 1,FEV1/FVC,HR,the activity of AChE of blood of contacting group were lower than the control group(P<0101).RMMSD of contacting group was higher than the control group(P<0101).Conclusion Low concentration of TDI had effect on the respiratory function,the activity of AChE and RMSSD in exposed workers.