The invention provides a three-redundancy digital double-pendulum servo system with low-temperature hydrogen as energy, belongs to the field of servo systems, and particularly discloses a multi-redundancy valve control servo mechanism used for thrust vector control over a liquid hydrogen and liquid oxygen engine of a launch vehicle. The three-redundancy digital double-pendulum servo system comprises a first servo mechanism, a second servo mechanism and a three-redundancy controller, wherein a low-pressure self-seal of the first servo mechanism is connected with a low-pressure self-seal of the second servo mechanism; a high-pressure self-seal of the first servo mechanism is connected with a high-pressure self-seal of the second servo mechanism; three-redundancy potentiometers of the first servo mechanism and the second servo mechanism are both connected with the three-redundancy controller; three-redundancy servo valves of the first servo mechanism and the second servo mechanism are both connected with the three-redundancy controller. The three-redundancy digital double-pendulum servo system with the low-temperature hydrogen as the energy is high in reliability, is designed in an overall self-service mode, conveniently achieves ground test and switching of sky and ground energy, and has the cold starting and control capacity.