Currently ammonia nitrogen pollution in surface water has become the most predominant problem in Changzhou.It was estimated that surface water accepted 17998.0t/a ammonia nitrogen in Changzhou by two years of monitoring and investigation and relevant information and scientific research.By calculation,farmland runoff contributed 32﹪ of ammonia nitrogen,while the upstream runoff contributed 30﹪ and the ruban domestic sewage,rural domestic sewage,industrial wastewater,urban runoff and large-scale livestock breeding accounted for less than 13﹪.Finally,countermeasures were proposed on how to reduce ammonia nitrogen in the surface water.