Parametric design is a method of three-dimensional forward design based on the internal connections and constraints of bridge structure design. This method can effectively improve the efficiency of structural adjustment and optimization. In the plan and preliminary design stage, the parametric design concept can be used to optimize the rationality, economy and aesthetics of the bridge structure to meet the social needs of the diversified development of the bridge at present time; in the construction design stage, by adjusting the independent variable parameters, It can flexibly adjust the detailed structure of the bridge and automatically interact with the two-dimensional design drawings, which greatly improves the design efficiency and quality. Based on the "R+GH" parametric platform, this paper proposes a parametric design process for bridge structures, and further verifies the practicability and efficiency of the design idea through the application of engineering cases.