The scale model test of long-span steel structure designed by the similarity theory often fails to reflect the mechanical properties of the prototype structure because of the simultaneous distortion of multiple parameters such as material and size. A response surface prediction model based on response surface method was proposed to correct the distortion parameters, and considering the difficulty of material processing and production cost, based on the similarity theory, a 1/2 hollow beam reduction model made of three different materials was designed and the beam section thickness was distorted. The errors before and after the correction of the multi-parameter distortion model were analyzed. The results show these as follow. The established response surface equation has good fitting accuracy and the ability to predict unknown parameters. Under the action of all levels of uniform load, after numerical simulation and equivalent stiffness theoretical calculation of the multi-parameter distortion steel hollow beam scaling model, the uncorrected scaling model has a large error in mapping the mechanical properties of the prototype structure, while the corrected response surface model significantly reduces the error. The scaled model with multi-parameter distortion can effectively predict the mechanical properties of prototype structures.