We focused on developing the correlation between the polymer microstructure, BHJ morphology and the photovoltaic properties of high performance all-polymer solar cells (all-PSCs). As model systems of modulating the molecular weight and the alkyl side chain of polymers, the polymer microstructure and the BHJ blend morphology of all-PSCs are systematically controlled, and thereby we produced high-performance all-PSCs system with 7% efficiency, which is the highest value reported to date. More importantly, our all-PSCs exhibited dramatically enhanced strength and flexibility compared with polymer/PCBM devices, with 60x and 470x improvements in elongation at break and toughness, respectively. The superior mechanical properties of all-PSCs afford greater tolerance to severe deformations than conventional polymerfullerene solar cells, making them much better candidates for applications in flexible and portable devices.