JJF 2104-2024 "Specification for calibrating seawater dissolved oxygen measurement meters" applies to the calibrating work of seawater dissolved oxygen measurement meters used in marine sites. This specification refers to the relevant specifications of JJG 196 on commonly used Glass gauges, GB/T 1 2763.4 on the investigation of seawater chemical elements and GB 17378.4 on marine monitoring. Dissolved oxygen measurement meters usually consist of dissolved oxygen Sensors, host and software, with temperature measurement elements to compensate for the effect of seawater temperature on dissolved oxygen concentration. According to the Measurement principle, they are divided into two types: electrochemistry dissolved oxygen meter and Optical inspection dissolved oxygen meter. The electrochemistry dissolved oxygen meter uses electrochemistry on the electrode surface to measure dissolved oxygen concentration, while the Optical inspection dissolved oxygen meter is based on the principle of fluorescence quenching, which reflects the dissolved oxygen concentration through Fluorescence intensity and lifetime. This specification aims to ensure the accuracy and Reliability of the seawater dissolved oxygen measurement instrument in the marine environment and meet the needs of marine scientific research and monitoring.