The regioregular conjugated polymer PSiFDF was designed and synthesized. PSiFDF contains a backbone comprised of SiIDT-FPT-DTSi-FBT (D1-A-D2-A) repeat units (DTSi= silolodithiophene, FBT = fluorobenzo[1,2,5]thiadiazole, SiIDT = silaindacenodithiophene) and strictly organized FBT orientations, such that the F-atoms point against the DTSi fragment. The optical bandgap of PSiFDF was calculated around 1.57 eV from thin films absorption spectroscopy. Owning to the introduction of FBT and the short alkyl chain along the polymer backbone, PSiFDF demonstrated quite small alkyl chain (~16.8 Å) and π-π stacking (~3.5 Å) distance and favorable “face-on” orientation by examination of thin films via grazing incidence wide-angle X-ray diffraction (GIWAXS) experiments. Most significantly, we find that PSiFDF:PC71BM blends exhibited similar photovoltaic property with highly efficient molecule donor materials. By adding only 0.5% DIO into chloroform, the blend can establish ideal interpenetrating network, and achieve an extremely high short-circuit current density (Jsc) of 17 mA/cm2, together with a maximum PCE of 8%. Comparison against a wide range of D-A narrow band gap conjugated polymers, our high-performing D1-A-D2-A polymer reveals the potential of this new class semiconducting materials as well as opportunity to study the correlation between molecular structures and blend morphology.