Aiming at the problem that the separation relationship between design parameters and linear elastic operators should be known in advance for the reduced basis method, a method based on inversion reduced basis method is proposed to solve linear elastic operators independent of design parameters. In the off-line stage, a low dimensional solution space is constructed without knowing the relationship between design parameters and linear elastic operators. Different design parameters are selected, and the linear elastic operators can be extracted from ANSYS software. The linear elastic matrix independent of design parameters is then solved by inversion reduced basis method. In the on-line stage, the calculation results can be obtained quickly when the new design parameters are selected. A planar frame structure was taken as an example, in which the results from the improved reduced basis method and the finite element method were compared, showing that the improved reduced basis method has high accuracy and the traditional application scope of reduced basis method is expanded.