In order to ensure the stability,balance and rudder responsiveness of submergedfloating unmanned vehicle in navigation,the electric steering device of a submergedfloating unmanned vehicle was designed to meet the needs of some project.The physical model of the electric steering device was established through CAD method,and the working principle of the steering device was analyzed mathematically.The parameter optimization design of the rudder blade was carried out.Finally,the resistance performance of the rudder blade was simulated by using HyperMesh and Fluent software.The analysis results show that the optimal design of the rudder blade parameters fully meets the project requirements.The design of the electric steering device of the submarinefloating unmanned vehicle provides reference for the future development of the submarinefloating unmanned vehicle.