The invention discloses a judgment method of a switch position of a high-voltage direct-current control protection system. The method comprises steps of firstly, using a closing signal and an openingsignal of a single switch as two input signals; allowing the closing signal and the opening signal passing through a first Not gate to pass a first AND gate, outputting and allowing an output signal and a closing position of the first AND gate to be subjected to logic operation successively, and using the exit thereof as the closing position for output; allowing the opening signal and a closing signal of a third NOT gate to pass through the second AND gate, outputting and allowing an output signal and the closing position of the second AND gate to be subjected to logic operation successively and using the exit thereof as the opening position for output; and when the input of the closing signal and the opening signal is 0, representing that there is a signal loss phenomenon and keeping theoutput of the closing position and the opening signal to be the states before the signal loss. According to the invention, problems of mistaken judgment and mistaken operation of the protection systemcaused by faults of a single element of a signal loop can be effectively avoided.