For lack of flexible description and the increasing complexity of data input, traditional modeling methods can not meet the demand of fast modeling for complicated bridge structures. Traditional methods are classified into the data based modeling and the graphic based modeling, and their disadvantages are discussed. On this condition, a new modeling method based on design drawings of AutoCAD is presented in this paper, which could fulfill the requirement of fast modeling and reflect the mechanic properties and internal relation of the structures. Especially, it can draw data from the AutoCAD lines automatically for analysis. The efficiency and reliability of the method has been proved by our software system WXQ developed for curved-skew bridges through a practical project.