A long-endurance self-powered ocean buoy includes a buoy body, a power generation device and a gas bag base; the power generation device is mounted at a lower end of the gas bag base and includes a housing, a first power generation assembly, a second power generation assembly and a storage battery; the first power generation assembly includes a plurality of mutually-communicated gas chambers, hydraulic bags and control integration units. The lowest gas chamber is filled with a volatile working medium which can generate gas pressure by volatilization to drive power generation fans in turbines on a vent pipe communicating adjacent gas chambers for power generation. The second power generation assembly includes a plurality of temperature difference energy modules with one end surrounded by a phase change material and the other end in contact with the housing, so as to increase the power generation efficiency.