Abstract: In this paper, a novel dual-band bandpass filter applied for WLAN application is proposed. The filter structure used open-loop stepped impedance resonators (SIRs) loaded symmetrical H-shaped stubs to achieve its good dual-band response. The filter structure has been fabricated and measured, the measurement performance showed good agreements with the simulation. And results showed that the filter had two passbands centered at 2.4GHz and 5.2GHz, which is agreeable with WLAN (IEEE-802.11a/b/g) application. And the final filter's size is 33.06mm×13.23 mm, which corresponds to a size of 0.26λg ×0.10λg, where lg is the guided wavelength at the centre frequency of the first passband, so that the filter has the characteristics of miniaturization.