A prototype system of mooring buoy for ocean seafloor observation is constructed, that, ocean buoy and underwater junction box are combined together with an Electro-Optical-Mechanical (EOM) cable. So, the seafloor observation data can transmit to the sea surface buoy through EOM cable, and finally, the data transmit to the shore through satellite and wireless communication. On the other side, sea surface buoy offers power with the wind and solar panel to underwater junction box. Compared to the traditional sea surface observational buoy, we redesign the communication model, so as to transmit the seafloor data to shore in the real time mode. The transmit communication is constructed as "Seafloor observation (underwater junction box) - Ethernet (underwater junction box) - Ethernet/Optical Switch - EOM cable - Optical/Ethernet Switch - Ethernet (buoy) - Beidou satellite/wireless communication (buoy)". According to the energy transmission property of EOM cable and the power supply demand of the seafloor, the wind/solar controller system and DC-DC convert modular is designed. We give the detail design and test result. In the test, we transmit the sea surface video and seafloor video in real time mode through wireless communication link. The reliability of the communication link is verified, and the feasibility of launch and recovery process is verified.