Abstract: In view of the high content of heavy metals in the sludge of a water purification plant for a long time,the plant company led the relevant departments to carry out a traceability investigation of heavy metal pollution.The fixed-point water and sludge were sampled, monitored and analyzed within the service area of the water purification plant. By analyzing the content of heavy metals in the discharge outlets of each point, the source of heavy metal pollution was identified. It not only provided data support and decision-making basis for the quality and efficiency improvement work of the company's subordinate water purification plants, but also provided a basis for judging whether the external drainage of upstream enterprises being in compliance with regulations. It created the conditions for the company's sludge disposal to follow the principle of "reduction, stabilization, and nononsense".