Children with excessive blood lead will have various systemic clinical manifestations, 1. The nervous system will show hyperactivity, short attention span and aggressive behavior, slow reaction, drowsiness, and motor disorders. In severe cases, they may also have incoherent speech and forgetfulness. The digestive system may include abdominal pain, constipation, diarrhea, nausea, and vomiting. 3. The hematologic system may have microcytic hypochromic anemia, and the cardiovascular system may have elevated blood pressure and irregular heart rate. 4. The urinary system may have urinary sugar and high phosphaturia. Late stage children may develop azotemia and other manifestations of renal failure.5. And subclinical lead poisoning mainly affects children’s intelligence, behavioral development and physical growth.