The invention provides a design and realization method of a redundant and fault-tolerant safety instrument control system based on a fieldbus and ARM (advanced RISC machines), comprising the following steps: by virtue of redundant and fault-tolerant configuration of a system power supply, input modules, a CPU (central processing unit) and output modules, four core processors communicate with respective and corresponding I/O (input/output) modules by a CAN (controller area network) bus so as to carry out field signal acquisition and control command output, and hardware 2oo4 redundant and fault-tolerant voting is carried out on the output signals of four channels on an output voting module, so that mis-stop of the system caused by single-channel hardware failure is avoided, the function safety level of the redundant and fault-tolerant safety instrument control system is ensured to reach SIL3 (safety integrity level 3), in-time and fast response and protection are carried out on dangerous states of protected field equipment, further a production device enters a predefined working condition of safe stopping, and the safety of staffs, equipment, production and the device is guaranteed.