Dissolved oxygen is the most important parameter in the biochemical process of aquatic environment. It is also often used as a tracer in marine research. The optical dissolved oxygen sensor is a high-performance, low-power in-situ sensor for measuring the dissolved oxygen. It has so many advantages: small size, low power consumption, fast response,high stability, etc. It can provide long-term stable, accurate and reliable dissolved oxygen measurement data, which can be widely used in marine environmental investigation and monitoring.