This paper takes an automotive cooling fan shroud as the research object.Taking the dynamic characteristics of original fan shroud as the goal to optimize the new fan shrouds structure.Based on the results of dynamic analysis of the cooling fan shroud,choosing the design variables and constraints reasonably.With the objective of maximization of first-order modal frequency and minimization of the cooling fan shrouds volume,using the global response surface method(GRSM) to run a muti-objective optimization and obtaining a modified design with Hyperworks platform.Redesigning the fan shroud according to the results of optimization.Compared with the original fan shroud,the modified fan shroud of new material has better dynamic characteristics and the mass of which decreased by 14.9%,achieving the goal of material replacement.This research method has a certain value of engineering applications.