In the past 30 years, the Bohai Sea's environment has undergone tremendous changes. The input of land-based pollution is the main cause of the deterioration of the Bohai Sea's environment. In order to study the spatial relationship between the pressure intensity of land-based pollution and the pollution of the sea area, the three transport spaces from the catchment area to the estuary of the sea and the affected sea area are overall considered. The hierarchical nested water pollution output zoning method is adopted to divide the Bohai Sea area into 23 land-sea integrated management zones, which have spatially linked land-based pollution pressures with pollution in the Bohai Sea. Based on the data of the land use, socio-economic statistics and pollution census, the total nitrogen emissions of five types of social and economic activities in the Bohai Rim region were estimated, and then the land-based pollution pressure of each sub-unit was analyzed. The results show that: 1) The total nitrogen emissions of social and economic activities around the Bohai Sea area are about 850, 000 tons, among which, agricultural and rural non-point source pollution is the main source of nitrogen pollution, accounting for 57.4% of the total emissions, while the contribution of industrial emissions to nitrogen pollution is limited, accounting for 7.4% of the total emissions, and the living emission of urban residents is outstanding, accounting for 35.2% of the total emissions. 2) The nitrogen emission intensity of each catchment areas of land source is spatially highly coupled with its corresponding sea area pollution, which indicates that, the 23 land-sea integrated management zones classified in this paper are reasonable and operable. 3) The pollution pressures between the 23 land-sea integrated management zones are huge. The sub-area land source pollution pressures in the surrounding areas of Liaodong Bay, Bohai Bay and Laizhou Bay are relatively high. The pressures in other subareas are relatively low. 4) The pollution sources in the main catchment areas have obvious differences. The source of pollution between various sub-areas is significantly different. The main source of nitrogen pollution in Bohai Bay is residents' living emissions, Liaodong Bay industrial pollution is relatively prominent, and Laizhou Bay agricultural non-point source pollution accounted for a large proportion. Considering the spatial difference of pollution source structure, the management of land-based pollution should take catchment area as a unit to manage and control major pollution sources. 5) The pressure of land-based pollution in the Bohai Sea is difficult to alleviate in a short term.