Abstract: Based on the surface nutrient data of Bohai Sea in 2019, seasonal variations of nutrient concentrations, N/P ratio and eutrophication status were analyzed and evaluated. Results showed that seasonal distributions of DIN and phosphate were obviously different. The highest and lowest average concentration of seasonal DIN appeared in autumn and summer respectively. The highest average concentration of seasonal phosphate appeared in autumn and other seasonal concentrations were similar. In terms of spatial distribution, concentration of DIN and its components (except NH₄-N) decreased from inshore to offshore, which were significantly affected by river input. Although the highest value of phosphate appeared in coastal waters such as Liaohe estuary, the distribution of phosphate varied greatly in each season, indicating that phosphate is jointly affected by land-based input and phosphorus endogenous cycle in the ocean. Compared with offshore, N/P ratios of inshore were much higher, indicating that the nutrition of inshore was P-Limited (N/P<16) while the nutrition of offshore may be N-Limited (N/P<16). Eutrophication status showed that eutrophication areas mainly focused on Liaohe estuary and excessive DIN was the main reason.