Based on data of nitrogen, phosphorus and silicon nutrient pools and hydrological parameters collected in the center of the Bohai Sea during July 2013, November 2013 and May 2014 cruise, we studied the nutrient pool distributions and the nutrient speciation transformations. The results showed that nutrient pools had a strongly seasonal variation characteristic affected by terrigenous input, phytoplankton uptake, transformation, turbulent mixing and release from organic matter decomposition. During high productivity seasons in spring and summer, nutrients showed a transformation trend from inorganic compositions to organic and particulate compositions, while the dissolved organic and particulate phase nutrient compositions decomposed and transformed into inorganic phase in autumn. In summer, the nitrogen and phosphorous nutrients concentrations were (37.43±10.09) μmol/L and (0.73±0.19) μmol/L, respectively, with dissolved organic compositions dominate. In autumn, the concentrations of nutrients and inorganic components increased significantly, and the dissolved organic and particulate components decreased due to the disturbance and organic matter decomposition release effects. The concentrations of the particulate nitrogen (PN) and dissolved organic phosphorus (DOP) were (1.78±1.05) μmol/L and (0.13±0.06) μmol/L, respectively, and both reduced by 66% compared with summer cruise, while dissolved inorganic phosphorus (DIP) increased 10.8 times to (0.54±0.20) μmol/L. In spring, the nutrient compositions changed significantly. Dissolved inorganic nitrogen (DIN), DIP and reactive silicate (SiO₃) reduced by 45%, 89% and 85%, respectively, because of phytoplankton absorption, transformation and particulate matters sinking. DON reduced by 36% that influenced by decomposition during autumn and winter, while PN and DOP increased significantly by 27% and 160% than those in autumn, respectively. The nutrient ratios in different nutrient forms showed that the inorganic nutrient phases were far away from the Redfield ratio which had an important impact on the dominant status of diatom species. The nutrient ratios of dissolved organic and particulate nutrients showed DOP, particulate phosphorus (PP) and silicon were more easily impacted by organic matter decomposition and disturbance compared with nitrogen species during the autumn and winter low productivity seasons, which plays an important role in alleviating the phosphorus and silicon limitation in the Bohai Sea, China.