The invention relates to a square billet cutting root coupling counting method and devices, and belongs to the technical field of continuous casting equipment of the metallurgy industry. The square billet cutting root coupling counting method adopts the technical scheme that the square billet cutting root coupling counting method comprises the following steps: realizing the up and down transitive relation between a first stage production system and on-site signals by a programmable logic controller (PLC), collecting cutting and clamping signals, preheat oxygen signals, cutting oxygen signals, horizontally moving signals of a cutting device, and a rotational speed singles of a casting blank roller way in a continuous casting system by the programmable logic controller, quantizing and coupling the above signals, judging the number of the cutting roots of a casting blank when the preset condition is entirely met, and then, sending the results to the first stage production system to be accurately accumulated. The square billet cutting root coupling counting method provided by the invention has the positive effects of easiness in operation, convenience in maintenance, reduction in maintenance and consumption of devices, accurate accounting, lower workload, and convenience in furnaces division and production cost settlement.