In response to the practical measurement requirements of marine hydrological environmental parameters, this article focuses on the sensing mechanism, research progress, performance indicators, and existing technical bottlenecks of various types of fiber optic ocean conductivity-temperature-depth (CTD) sensors, and also briefly introduces the research progress and engineering application of marine environmental parameter sensor arrays. Judging by the research progress at home and abroad, the fiber Bragg grating CTD sensor has strong stability and environmental adaptability. First, it has initially satisfied the demand of marine environmental engineering monitoring and has had important application value in the research of marine environmental parameter sensing arrays; while fiber-optic surface plasmon resonance (SPR) based CTD and tapered fiber-based CTD have high sensitivity so they have good potential for application in multi-parameter integrated monitoring of the marine environment. Finally, based on the brief description of the development needs of a new generation of marine monitoring networks represented by the “Marine Internet of Things”,it proposed the developing trend and technical requirements of all-optical sensors for marine environmental parameters, which will provide scholars engaged in related research with reference materials and ideas.