Reversibility and durability have become new bottlenecks for conjugated polymers to realize "stretchable" semiconducting devices. Therefore, the correlation between microstructure and mechanical properties requires explicit delineation. Herein, the deformation and fracture mechanisms of DPP-TVT (poly [2,5-bis(4-decyl tetradecyl) pyrrolo [3,4-c]pyrrole-1,4-(2H, 5H)-dione-(E)-1,2-di (2,2 '-bithiophen-5-yl)ethene)'-bithiophen-5-yl)ethene) films with various degree of lamellar order were investigated from microscopic view. In the medium ordered films, the lamellae and amorphous phase cooperate to form the fibrous network structure in respond to tensile deformation. When recovered, this fibrous network could deform and being compressed, providing an efficient stress transfer pathway to accommodate the residual strain. Therefore, the medium ordered films did not form cracks even under 100 cycles of 50 % strain. However, in near-amorphous films, the uniformly aligned chains in stretched films were difficult to reorient under compression, resulting in the formation of large wrinkles and poor fatigue resistance. And the highly ordered films generate cracks both under single and cyclic stretch due to lacking of stress dissipation pathways. This study lays the groundwork for enhancing the mechanical robustness of conjugated polymer films.