Land-sourced sewage outfall is one of the main marine pollution sources. Monitoring of land-sourced sewage outfalls is the main content of marine environmental monitoring. However, due to the limitation of remote sensing technology, there are very few reports about land-sourced sewage outfalls monitoring using remote sensing technology, although it is the main information dectection technology for a large area. To meet the needs of land-sourced sewage outfalls monitoring, this paper proposed a novel land-sourced sewage outfalls monitoring method using remote sensing technology by referencing to the current "land-sourced sewage outfall and adjacent marine ecological environment monitoring Guide" (HY/T086-2005) of China. Considering the ability and the economic effectiveness of different satellite data, multi scale remote sensing data was used in this method. With multi scale remote sensing data, the observed ground water quality parameters and spectral data, water quality parameters were extracted. Then Bohai Sea water quality was assessed by water quality parameters and spectral characteristics. And the key monitoring area was found out based on the result of water quality assessment. Finally, positions of land-sourced sewage outfalls were detected using high resolution remote sensing data in the key monitoring area. Validation of this method was conducted in the circum-Bohai region, China, and high positioning accuracy was acquired. Using this method, efficiency of land-sourced sewage outfalls monitoring can be improved greatly, while the cost and workload can be substantially reduced.