Abstract: When high speed train passes through tunnel, aerodynamic effect will be induced.Setting hood at tunnel entrance is one of the convenient and effective measures for controlling aerodynamic effect.While the hood usually lay at tunnel entrance, in a long run, the aerodynamic load on the structure also should not be overlooked.In this paper, using Ansys-workbench simulation platform, the fluid structure coupling character induced by aerodynamic load on single top opening hood was analyzed.The research results showed that the extra-pressure stress induced by aerodynamic load was notable.To the train of running speed 350 km/h, the induced extra pressure stress on hood structure can reach 80 kPa.On the tunnel hood, the region around the openings appeared a relative high extra pressure stress.Since the tunnel is used for double railway line, the variation law of extra pressure stress on the tunnel hood inertial side wall of close to and far from train is almost same, while the stress pressure on inertial side wall of close to train is a little larger than that on the other side.Like the compression wave transportation in tunnel, the extra pressure stress induced by aerodynamic load also shows reciprocating transmission characteristics.The reason of stress concentration around the hood openings was deduced and showed that hood structure condition is the intrinsic fact for resulting in the detrimental effect.These conclusions on aerodynamic load are advisable for tunnel hood design and safety checking.