With the in-depth development of marine ranching construction, dynamic monitoring and assessment of marine ecological environment and fishery resources have become particularly important, and mobile autonomous monitoring is one of the feasible solutions. Aiming at the problems of low efficiency, poor flexibility, high cost and difficult transportation and delivery of existing monitoring methods, a combined unmanned monitoring ship equipped with multiple types of monitoring equipment was proposed. The hull structure design and monitoring instrument installation mechanism design were carried out, and the counterweight mechanism design was carried out considering the hull draft load and stability. Based on the computational fluid dynamics method, the hull resistance performance was simulated and calculated, and the underwater thruster selection was completed, and the static strength finite element analysis was carried out on the unmanned ship connecting bridge structure in high waves, and the strength of the hull structure could resist the 4th level wave. The test results show that the unmanned monitoring vessel has stable operation without interference, the design draft is 0.25 m, the speed is 2.5 m/s, and it can be competent for marine ranching work sea conditions. The monitoring equipment works stably after being installed, and can monitor underwater fishery resources, explore underwater terrain, monitor water pH, temperature and dissolved oxygen in real time. This study provides technical support for ocean dynamic, real-time monitoring and digitalization, and provides a low-cost and reliable implementation scheme for the design and research of marine ranching combined unmanned monitoring vessels.