The invention relates to a dual-redundant unmanned ship ship-borne control system and method based on an ARM. The system comprises an information collection system, a first arbitration switching system, a second arbitration switching system, an execution mechanism, a first ARM processor, a second ARM processor, a communication system and a power supply. The task level synchronization is realized by the two ARM processors. The dual-redundant designs of all sensors are made. The data of two paths of sensors are transmitted to two ARM processors at the same time to carry out comparison, correct data is selected to carry out task operation, and a comparison point is set in the task operation. The corresponding data is subjected to consistency judgment, if the corresponding data is inconsistent, the arbitration switching systems carry out fault diagnosis on the two ARM processors, a failed ARM processor is isolated, and at the same time an ARM processor with normal operation is selected to control output. According to the dual-redundant unmanned ship ship-borne control system and method, with hardware redundancy as a basis, with software redundancy, information redundancy and time redundancy as a supplement, the reliability, stability and safety of the unmanned ship ship-borne control system are effectively improved, the safe and stable operation of an unmanned ship is ensured, and various complex tasks are smoothly completed.