In consideration of the limitation of TRSM (typical response surface method), a MRSM (modified response surface method) which was based on the inner connection between optimization parameters and appointed response was put forward. Several numerical experiments were conducted, and the results were compared with the predicted values of both models. The comparative results show that the MRSM′s predicted values are more uniform than TRSM′s and the max error absolute value is smaller than TRSM′s. By using genetic algorithm, the MRSM is optimized whose aim is to minimize the weight of flange and an ideal result is obtained.