Polymer solar cells (PSCs) are a promising alternative for clean and renewable energy due to their potential to be fabricated onto large area,light-weight flexible substrates by solution processing at low cost.Our recent progress in the molecular design of p-type conjugated polymers containing multi-fused ladder-type structure and the n-type fullerene derivatives containing cross-linkable styryl or epoxy groups will be presented.Both ladder-type conjugated polymers and n-type fullerene derivatives are used to fabricate high efficient bulk heterojunction PSCs.The cross-linkable fullerene derivatives are also used to fix the morphology of bulk heterojunction (BHJ) layer so as to improve the stability of PSCs.Finally a series of novel DA copolymers were developed by utilizing pyrene-modified porphyrin as complementary light-harvesting unit (LHU).