Abstract: Based on the method of arc-length parameter space, namely mapping the initial CAD data model into the parameter space, after adjustment, then mapping back to the physical space，preserving surface characteristic in the process of transformation will not change the model surface shape. The method is applied to the surface grid of automobile body and obtains the predictive effect. The method of arc-length parameter space provides a good solution for the surface grid of complex geometry contour, and establishes the foundation for the further analysis carried out.

Key words: Arc-length parameter space, Automobile body, Surface grid