Abstract: According to the miniaturization and high performance, the characteristic of a second-order bandpass filter (BPF) with in-line ports based on dual-mode square-shaped resonator is researched, and higher-order BPFs with in-line ports using single-mode resonators and dual-mode resonators are proposed. The proposed filters can be modeled by the box-like coupling scheme, which can realize flexible frequency responses. Moreover, the positions of transmission zeros (TZs) can be easily adjusted to satisfy different applications. An additional TZ can be achieved by the proposed filter in box-like topology for the parasitic coupling in the diagonal cross-coupling path. To verify the proposed structure and design method, third-order and fifth-order filters with center frequency of 5.2 GHz are designed, fabricated and measured. The responses of coupling matrix, simulated and measured results are in good agreement, which demonstrates the feasibility of the proposed filters with high performance.