Doping　is　a　recognized　method　for　enhancing　catalytic　performance.　The　introduction　of　strains　is　a　common　consequence　of　doping,　although　it　is　often　overlooked.　Differentiating　the　impact　of　doping　and　strain　on　catalytic　performance　poses　a　significant　challenge.　In　this　study,　Cu-doped　Bi　catalysts　with　substantial　tensile　strain　are　synthesized.　The　synergistic　effects　of　doping　and　strain　in　bismuth　result　in　a　remarkable　CO2RR　performance.　Under　optimized　conditions,　Cu-1/6-Bi　demonstrates　exceptional　formate　Faradaic　efficiency　(＞95%)　and　maintains　over　90%　across　a　wide　potential　window　of　900　mV.　Furthermore,　it　delivers　an　industrial-relevant　partial　current　density　of　-317　mA　cm(-2)　at　-1.2　V-RHE　in　a　flow　cell,　while　maintaining　its　selectivity.　Additionally,　it　exhibits　exceptional　long-term　stability,　surpassing　120　h　at　-200　mA　cm(-2).　Through　experimental　and　theoretical　mechanistic　investigations,　it　has　been　determined　that　the　introduction　of　tensile　strain　facilitates　the　adsorption　of　*CO2,　thereby　enhancing　the　reaction　kinetics.　Moreover,　the　presence　of　Cu　dopants　and　tensile　strain　further　diminishes　the　energy　barrier　for　the　formation　of　*OCHO　intermediate.　This　study　not　only　offers　valuable　insights　for　the　development　of　effective　catalysts　for　CO2RR　through　doping,　but　also　establishes　correlations　between　doping,　lattice　strains,　and　catalytic　properties　of　bismuth　catalysts.