Abstract: With the development of fractional calculus, the passive realization of fractional-order networks has gradually become a research hotspot. In this paper, the bivariate passive network synthesis method is improved. Combined with variable substitution, the passive realization problem of two-element fractional-order immittance functions is solved. The calculation process of the proposed method mainly involves the differentiation of immittance functions, matrix factorization and the synthesis of univariate immittance matrices. Finally, two numerical examples are provided to illustrate the detailed calculation procedures.