Objective To examine the effect of oral external suction on environmental pollution of microorganism in dental clinic.Methods Aerobe was counted na observation index of air contamination and air sample of the area leveal 1m and 2.5 m,hight 1m,which using oral cavity collectors of aspirator or not was collected by the method of sedimentation.Results The datum of the group with oral cavity collectors of aspirator was much lower than the group without it.Conclusion Environmental pollution from tooth treatment in dental clinic can be reduced by using oral extemal suction.