A spoof surface plasmon polaritions (SSPPs) microwave band pass filter with stepped slot structure is designed by using FDTD method. The filter is composed of four sections, in which the second section (i.e. the stepped impedance slot section) is the transition section. The novel periodically arranged stepped impedance slot design can enhance the confinement effect of microwave band sub-wavelength, improve the pass-band characteristics and the ability of resisting electromagnetic interference of the SSPPs band pass filter. The transmission and reflection properties of the SSPPs filter in the microwave frequency range are investigated by FDTD method. The results show that through adjusting the geometrical dimensions of the stepped impedance slot structure as well as the coupling gap parameters in the transmission line, the bandwidth and suppression characteristics of the filter can be flexibly controlled and the filter has strong resistance to the space electromagnetic interference.