Abstract: paper took Tacoma Narrow Bridge accident caused bywind vibration for an example, researched mechanism of the bridge vibrationon the H-type bridge deck and analyzed flow symmetry breaking and conditionsof the bridge vibration induced by the flow around. Based on the actual sizeof bridge deck, two-dimensional numerical calculation was set up by Fluentsoftware. The results showed that the low pressure area was gradually formedfrom the middle region, moved down wind and changed alternately andperiodically on the upper and lower bridge deck; Secondly, the bigger thewind speed, the smaller the variance period of bridge resistance force andlift force and the rate of period variance; Thirdly, the variance period oflift coefficient was two times of resistance coefficient, and the varianceperiod of lift coefficient was around 31.5s, with the wind velocity is19m/s.