The invention discloses a method and a system for monitoring the fuel ratio of a blast furnace in real time, which is characterized in that: the method comprises the following steps: (1) calculating amonitoring value of Si content in molten iron of the current heat and inputting the monitoring value to a computer; (2) calculating a control value RLB of the fuel ratio by a fuel ratio calculation module; (3) obtaining a detection value Ls of a baiting speed; (4) inputting the control value RLB of the fuel ratio, a detection value K of coke ratio and the detection value Ls of the baiting speed to a calculation module of a coal injection speed for calculation, and outputting a control value M of the coal injection speed; and (5) inputting the control value of the coal injection speed to an industrial control computer; and issuing a command of coal injection amount to coal injection control equipment of the blast furnace according to the control value of the coal injection speed. The method and the system simulate the operating thinking of a blast furnace operator through the computer, standardize the operating action of the operator, reduce the operating randomness varying from personto person and reduce the failure rate of the operator to the maximum extent.