The railway double-track continuous bridge vertical load-carrying frequency is theoretical derived with the vehicle-bridge system mode1. The vertical load-carrying frequencies of the 40 m+4×72 m+40 m party pre-stressed concrete continuous box-girder bridge are calculated, when two trains with 20 same high-speed passenger vehicles are traveling on the bridge from both ends. The change regularity of this double-track continuous bridge vertical load-carrying natural frequency with two trains on it is similar with that of the single-track simply supported bridge and this bridge as one train on it. This bridge vertical load-carrying frequency when two trains on it is smaller than that only train on it. The maximum deviation percentage between the vertical load-carrying natural frequency and the vertical natural frequency is 1.17837%.This bridge vertical load-carrying frequency can be replaced by its natural frequency, and there isn’t obvious error. If the vertical load-carrying frequency should be calculated, it can be replaced by the average value.