Abstract: Total phosphorus of three columnar sediments in Zhejiang offshore was measured. A sequential extraction method (SEDEX) was adopted to measure phosphorus of 5 forms in the columnar sediments. ²¹⁰Pb method was used to measure the deposition rate. Age-dating results were combined with some climatic or human activity events to analyze the vertical distribution characteristics of total phosphorus, inorganic phosphorus and phosphorus of 5 forms, and degradation of organic phosphorous. The research results indicated that vertical distribution characteristics of phosphorus in various forms at different stations were different, relating to the sedimentary environment and diagenesis. Organic phosphorous in the core sediments showed the rapidly declining trends in the surface layer or sub-surface, indicating that degradation of organic phosphorous mainly occurred in the surficial aerobic zone and sub-surface.