In this paper we simulate a band-pass filter, it is a 23 layers multi-layer structure and with 28 vias. The simulation is performed by integration equation based on method of moments (MoM). To speed up the calculation, some new techniques are used. Using triangular-quadrilateral hybrid basis functions to reduce the unknowns. Embedding the unknown edges with more than two connecting cells to simple the problem. Taking the absorbing boundary condition in MoM codes to treat the vias connected to ground planes. Fast Green's function via spectral interpolation is used to calculate the Green's function efficiently. Compared with the experiment results, the analysis we used for the filter is not only efficient but also accuracy.