Since　the　light　harvesting　of　the　organic　solar　cells　(OSCs)　is　limited　by　the　ultra-thin　active　layer　film　due　to　the　low　carrier　mobility　of　the　organic　materials.　This　study　presents　a　tractable　and　cost-effective　method　for　enhancement　of　the　light　capture　of　OSCs.　A　pyramid-shaped　micron-structured　polydimethylsiloxane　(MSTPDMS)　anti-reflection　film　was　pasted　on　the　back　surface　of　the　OSCs.　The　MST-PDMS　film　can　reduce　the　reflectivity　of　incident　light　and　enhance　light　capture.　Comparing　with　that　of　the　devices　based　on　the　normal　indium　tin　oxide　(ITO)　glass　substrates,　the　performance　of　the　devices　with　MST-PDMS　was　significant　improved.　The　size　of　the　pyramid　is　an　important　factor　to　the　performances　of　the　devices.　The　short　circuit　current　density　could　increase　mostly　without　sacrificing　the　open　circuit　voltage　and　fill　factor,　when　the　width　of　the　pyramid　is　9　mu　m,　and　a　maximum　power　conversion　efficiency　(PCE)　of　PTB7-Th:　PC71BM-based　OSCs　reaches　to　10.18%.　Compared　with　that　of　the　device　without　the　anti-reflection　film,　PCE　was　increased　by　17.96%.　Further,　the　OSCs　with　the　pyramid-shaped　MST-PDMS　exhibits　a　relatively　high　hydrophobic　properties　leading　to　a　better　stability　of　the　devices　at　the　ambient　environment.