In this paper, a miniaturized bandpass filter based on low temperature co-fired ceramic (LTCC) technology is proposed. The miniaturization is achieved by two double folded substrate integrated waveguide (DFSIW) resonant cavities. By interconnecting LTCC three-dimensional structure, the resonant cavities can be stacked vertically. Compared with the conventional SIW filter, the size is reduced by 75.6%. The experimental results show that the low insertion loss and good selectivity are achieved. The proposed miniaturized bandpass filter is promising for 5G application.