The invention discloses a triple-redundancy control computer and a fault-tolerant control system. The triple-redundancy control computer comprises a switching value voting array module and three completely-independent sub-computers. The switching value voting array module receives switching value control signals output by the three sub-computers, backs up the switching value control signals, and outputs switching value power control instructions through a hardware voter. Each sub-computer determines a left computer and a right computer which correspond to the sub-computer according to a left and right computer role definition table. Each sub-computer comprises a synchronous module, a self-detection module, a left computer detection module, a right computer detection module, a duty control module, a host module and a switching value control output module. According to the triple-redundancy control computer and the fault-tolerant control system, on the basis of meeting the requirement of the system for hard real-time performance, more single-computer fault modes can be tolerated, the overall high reliability of the system is improved, and the software and hardware expenses are reduced.