A kind of wideband differential bandpass filters on the multimode slotline resonator has been proposed. In virtue of the hybrid microstrip/slotline structures, the common mode (CM) signals can be intrinsically rejected in the topology. Multiple modes of the slotline resonator are excited to construct the wideband passband in differential-mode (DM). Further, a novel design method has been deduced based on the synthesis of the general highpass filter. In this method, turn ratios of the transformers in the circuit models are estimated and taken into consideration to optimize the filters. Finally, two filters with different bandwidths and in-band return losses are designed to show the flexibility of the filters and support the design method.