Abstract: A novel low temperature co-fired ceramic（LTCC） bandpass filter（BPF） with high-order harmonic suppression is proposed. The circuit of this filter is composed of five resonant cavities by magnetic coupling,and each resonant cavity is realized by a metal column loading a metal sheet. The large capacitance of metal sheets to the ground enhances the slow-wave effect of the structure itself,which thus effectively reduces the volume of the filter,improves the attenuation outside the band and realizes the high-order harmonic suppression. By the three-dimensional electromagnetic simulation software HFSS modeling and simulating,a bandpass filter with a center frequency of 5.14 GHz and a bandwidth of 1.48 GHz is designed. The attenuation in the stop band from 9.15 GHz to 30 GHz is better than 70 d B,and high-order harmonics are suppressed to 30 GHz. The volume is only 5.4 mm×2.2 mm×1.2 mm. The evaluation results show a good match with the simulation results. Compared with some existing harmonicsuppression filters,the filter designed in this paper has stronger attenuation degree,wider suppression range and more advantages in application.