Analyzing uracil-DNA glycosylase (UDG) activity is essential for understanding DNA repair mechanisms in disease progression and treatment. This study presents a dual-mode DNA nano-stage biosensing platform integrating electrochemiluminescence (ECL) and electrochemical impedance spectroscopy (EIS) for highly sensitive and specific UDG detection. A DNA-prism-modified electrode immobilizes UDG-responsive elements, forming a stable and efficient detection interface. Upon UDG cleavage, released DNA fragments initiate rapid nano-stage assembly, significantly amplifying the signal output. ECL signals are produced by embedded [Ru(phen)