The safety of the construction and operation of cross-sea Bridges is seriously threatened by the extreme wave load near the sea and has a great impact on regional traffic. In order to clarify the stress characteristics of bridge main beams in off shore areas under extreme wave action, a physical model test with a scale ratio of 1∶20 was carried out using an indoor wave making tank to study the time history curve and peak characteristics of the horizontal wave force, vertical wave force and overturning moment of T-beam under the combined conditions of different test water depth, wave making speed and submerged coefficient. Then, considering the above three factors, the parameter sensitivity analysis of wave load characteristics of T-beam is carried out. The results show that: (1) The wave force of T-beam is significantly affected by water depth. With the increase of submerged depth, the vertical wave force at peak time decreases first and then increases, and the direction changes from upward to downward; The change trend of horizontal wave force at peak time is consistent with that of vertical wave force, but the direction is unchanged. The overturning moment increases first and then decreases, and the peak value is the largest in semⅠ-submerged state. (2) The vertical wave force on the lower panel of the roof is larger, while the reverse vertical wave force on the upper panel of the roof is larger for the T-beam in the non-submerged state; The two beams whose waves reach first mainly bear larger horizontal wave force and reverse horizontal force; (3) For the T-beam in the completely submerged state, the beam on both sides of the model bears a larger positive horizontal force, while the second beam on the wave facing side bears most of the reverse horizontal wave force; (4) Considering the three influencing factors, the parametric sensitivity analysis results show that the wave load of T-beam is significantly affected by wave velocity and inundation coefficient, while the law of wave altitude influence is more complex, and no obvious law is reflected. In this paper, the extreme wave load distribution and action characteristics of cross-sea T-beam are studied, and the main factors affecting the wave force and overturning moment of T-beam are discussed. The research results are of great significance to the safety of cross-sea bridge structure.