Southern Bohai Sea sediment types and redox environments were studied by using the new concepts of “Grain Size Label (GSL)”and“ Redox Degree (ROD)”.The GSL, the pure chemical standard, has advangag for studying sediment grain size. The ROD gives a quantitative classification to marine sediment redox environments. The main results were follows: The mud (silt clay ) is the first and silt is the second in surface sediments. but silt is the first and mud second in the 1.50m sediment layer. Reduction is the characteristic in the two layers sediments. The main oxidation regions centered between the estuary of the Luanhe River and the area west of Laotieshan.