GB 3097-1997 is a seawater quality standard. In order to protect the marine ecological environment, the standard divides seawater quality into four categories according to the function of sea area use and protection goals. For each type of water quality, strict limits are set for dozens of indicators such as chemical oxygen demand, dissolved oxygen, inorganic nitrogen, and petroleum. It covers physical, chemical, biological and other water quality requirements, and clarifies the sampling method, Frequency and analysis and measurement specifications for water quality monitoring. It is suitable for all kinds of sea areas, providing an important basis for seawater quality evaluation, marine resource development and management and pollution prevention, and safeguarding marine ecological equilibrate and sustainable development.