To understand the current mercury exposure level of the residents living within the Second Songhua River basin, 120 hair samples were collected from Qianguo Irrigation Area in the downstream of the basin. The total mercury contents in hair samples were determined and the influencing factors were analyzed. The results showed that the range of the total mercury contents was 0.15-1.01 mg/kg and the average value was 0.56 mg/kg. The average hair mercury content of male residents was 0.55 mg/kg while that of female residents was 0.60 mg/kg. The total hair mercury firstly increased and then gradually decreased with the increasing of age. The lowest mean hair mercury value(0.47 mg/kg) was detected in the residents with the age of 0-20 and the highest mean hair mercury value (0.73 mg/kg) was detected in the residents with the age of 40-50. Among the other factors influencing human hair mercury contents, the gender, height, body weight, fish consumption, smoking and wine-drinking showed no significant correlations with the hair mercury contents. Only one hair sample was detected with greater mercury content than the limitation (1.00 mg/kg) established by USEPA, suggesting low mercury exposure risks in the area. This investigation indicated the historical pollution of the Second Songhua River hadn't lead health risks to the residents of the region and the irrigation using water from the river after the building of the Hadashan Reservoir would cause low environmental risks.