The in-situ seawater TN and TP analyzer is an in-situ monitoring device used to detect the total nitrogen and total phosphorus concentration in water such as ocean, near shore, and estuary. It provides users with accurate, continuous and stable data to achieve water various research works including eutrophication evaluation, phytoplankton growth research, early warning of ecological disasters such as red tide, and real-time monitoring of water environment. It can be integrated in buoys, multi-parameter monitoring systems, or run onboard, shore-based deployment to achieve unattended in-situ online monitoring. The instrument is equipped with system leak warning, detection threshold alarm and other functions, it can add automatic storage equipment to prevent data loss during transmission or remote storage failure.