Bohai is an important supportive system of Bohai regional economic development, with the Bohai coastal region increasing intentive economic development, Bohai environmental pressure is also growing,which is the world's most serious air pollution areas.Bohai regional development plans are included in the national overall development strategy and the area has an important position in the country. A series of water problems such as water shortage, ecological degradation and water pollution faced greatly restrict the economic and social development of the region.Land-based source of pollution is one of the main causes of pollution in the Bohai sea coastal waters, and drainage channel is the main contributor of Land-based source of pollution. In this paper,we choose the main pollution sources and channel section as object of the study of Dagu river which is the main pollution river in Tianjin Bohai area , on the basis of understanding the pollution source emission characteristics,layout sample point and monitoring the water quality changes both of upstream and downstream at point sources of pollution ,analysis the influence of river section and contribution which made by the source points of pollution.Based on single factor evaluation method of principal component analysis method for analysis,using the principle of location selection choose Tianjin Dagu river pollution source location and determine the sampling point.Investigation of historical data and field monitoring of toxic and harmful substances in sewage, to determine the region priority pollutants list and the major pollution sources.Set sampling point both in the upstream and downstream of pollution source.And in order to provide basis for reducing and limiting emissions and setting the control strategy.Some corresponding land-based source of pollution control method and pollution prevention and control strategies was put forward in the paper. In order to improve the efficiency of development and utilization of water resources and protect the environment in Tianjin.