1. A computer system, comprising: a central processing unit; a storage device storing one or more programs, the one or more programs comprising: an acquisition module configured for reading data corresponding to a tabular W element format in the storage device, and adding data of the tabular W element format file using an interpolation algorithm; a first parameter transformation module configured for transforming a frequency-dependent transmission matrix into an N-port network matrix describing electrical properties of a multi-input and multi-output network; a second parameter transformation module configured for transforming an N-port network matrix into a S-parameter matrix, a diverging matrix describing relationship between an incident voltage wave and a reflective voltage wave in a high frequency circuit; a parameter determination module configured for determining a range of frequency of a s-parameter, and for determining numbers of pole-residue, times for recursion and durable maximum system errors in the equivalent circuit simulation; an equivalent circuit production module configured for performing a vector fitting algorithm, producing a rational function matrix composed with s-parameters, and producing a general SPICE equivalent circuit based on the generated rational function matrix.