Abstract: On the basis of the traditional microstrip structure along with the rejection and slow wave suppression characteristics of step-impedance shunt stubs（SISS），a new type of defected structure of microstrip line with SISS（S-DMS）was presented. A harmonic suppressed dual-band band-pass filter was designed and fabricated employing the S-DMS and it was simulated and optimized by using HFSS. The physical filter was fabricated on the basis of simulation. It is observed that the dual-band band-pass filter operates at 3.5 GHz and 8.5 GHz with insertion loss of 0.45 dB，2.7 dB. And the 3 dB bandwidth achieves 550 MHz and 260 MHz respectively.The measured results that the inhibit out-of-band is lower than to 40 dB，are consistent well with the simulation ones. The results exhibit that the dual-band band-pass filter has good harmonic suppression，small in-band attenuation and wide and deep stopband characteristics.