The invention relates to a comprehensive control system for a nuclear power plant BOP (Balance Of Plant) process and a method thereof, the system comprises a BOP comprehensive control room shared by all subitems of a BOP system, a man-machine interface device is arranged in the BOP comprehensive control room, a control cabinet communicates with the man-machine interface device in the BOP comprehensive control room through an industrial Ethernet, remote I/O (Input/Output) cabinets used for being connected with field equipment are arranged in all sub-items of the BOP system, the remote I/O cabinets are connected with the control cabinet through a bus, and video/image recognition equipment is arranged in all the sub-items. According to the invention, an independent control room of each subitem is cancelled, so that the number of operators can be reduced, signals sent to a main control room of the nuclear power plant can be reduced, the cost of a main DCS (Distributed Control System) can be reduced, and the burden of operators in the main control room can be reduced. In cooperation with the bus and remote I/O technology, the number of cables can be greatly reduced, and the cable laying cost is reduced. In cooperation with a video/image recognition function, inspection personnel can be reduced, and the operation and maintenance cost of the nuclear power plant is reduced.