A new quasistatic analysis of microstrip line structures with multidielectric layers is presented, using a hybrid approach that combined the Galerkin finite-element method and the conformal-mapping technique. Wheeler's mapping function is adopted, which overcomes both the problem of infinite field extension and the field singularity difficulty around the conductor edges. Numerical results for effective dielectric constants, characteristic impedances, charge distributions, and field distributions for various multilayer microstrip line structures are presented and discussed. Comparisons are also made of the computed results with the available quasistatic ones, and good agreements are obtained.