Conventional conjugated polymers face the critical challenge of achieving simultaneous optimization of electrical and mechanical properties. This study focuses on siloxane-side-chain-functionalized diketopyrrolopyrrole (DPP)-based conjugated polymer (DPP-4Si) blended with hydrogenated styrene-butadiene block copolymer (SEBS). Through precise control of film preparation and microphase separation structures, we developed high-performance elastic semiconductor films with a maximum mobility of 1.08 cm2·V^-1·s^-1. Fully stretchable transistors fabricated using the optimal blend ratio demonstrated remarkable electromechanical stability, maintaining over 72% current retention even under 100% tensile strain, showcasing exceptional stretchability.