Abstract: General formulae for the equivalent circuit parameters of multi-fin-line structures are derived by using field matching technique and eigenvalue concept. Several inductive fin-line structures are analysed with this formula. Inductive parameters of the equivalent circuit of these structures decrease as the number of the fins increases and the thickness of the fins becomes greater. When frequency goes higher, the circuit parameters x, and xp become bigger. The parameters decrease as the distances between each two metal fins gocs further apart. With different moe number considered in the computation, the inductive parameters of dielectric fin (r=2.22) sandwiched in two metal sheets are analysed. The results show that then the mode number in continuous region and discontinuous region are greater than 20 and 80 respectively, errors due to truncation are less than 1%. In the case of single metal inductive fin and dielectric fin sandwiched in two metal sheets, the calculated data with this method are in good agreement with those calculated by variation method and S parameter method respectively.