The present disclosure relates to a speed control system of a railway vehicle in consideration of a braking characteristic, and more particularly, to a speed control system of a railway vehicle in consideration of a braking characteristic, which calculates in real time a time-to-target-speed-crossing (TTTSC) that is a time required for a speed of a train to exceed a speed of an automatic train operation (ATO) profile through a future speed estimation of the train, and controls the speed of the train to be interlocked with the TTTSC.