In this work, a double-layered spoof surface plasmon polariton (DLSSPP) transmission line (TL) was utilized as the main TL. Resonators is loaded onto the main TL to design a lowpass filter with a bandstop functionality at the center frequency of 6 GHz. The filter can operate within the frequency range of 0 GHz–9 GHz, exhibiting high efficiency and compact structure. The L-shaped resonator adopted a series structure, where the series connection of capacitance and inductance generates a transmission zero at 6 GHz, thereby achieving the stopband functionality. Furthermore, through analysis of the periodicity of the port impedance of the L-shaped resonator, it is found that adjusting the transverse structural parameters of the resonator can generate multiple resonance points, thereby enabling the filter to have multiple stopbands. To validate the accuracy of the proposed filter, physical filters in this frequency range are fabricated and tested, showing excellent agreement between the measurements and simulations.