The invention provides an on-line real-time mechanical property prediction method based on hot rolled steel coil production processes, and belongs to the technical field of metallurgical industry manufacturing and informationizing. A prediction model is built for mechanical properties of a hot rolled steel coil on the basis of historical true technological parameters, and on-line single prediction and curve prediction on the mechanical properties of the steel coil are achieved through the prediction model. On one hand, massive historical technological parameters are analyzed and summarized to deduct the stable and efficient property prediction model. On the other hand, management and property prediction are conducted on the model, real-time on-line mechanical property prediction is conducted on the produced steel coil, single prediction data is uploaded to an MES three-stage system, and curve prediction data is uploaded to a quality judgment system. Accordingly, property prediction and judgment full automation are achieved, the property examination and labor cost is reduced, and the enterprise production efficiency is improved.