Abstract: 8-Hydroxy-2’-deoxyguanosine (8-OHdG) is an important DNA damage marker, which can reflect the degree of oxidative damage in human body. In this study, a LRET-based label-free upconversion fluorescent probe was constructed based on the Luminescence resonance energy transfer between amino-functionalized upconversion nanoparticles (UCNPs) as the energy donor and gold nanoparticles (AuNPs) as the energy acceptor. As the AuNPs can induce the fluorescence quenching of UCNPs at 545 nm, and 8-OHdG can produce nonspecifically induced clustering of AuNPs, the fluorescence intensity of UCNPs is altered, which renders the detection of 8-OHdG in urine matrix. The developed method is simple, sensitive, and workable over a wide pH window. When the concentration of AuNPs solution is 1.34 nmol·L⁻¹ and the pH is 2~7, the 8-OHdG can be sensitively detected both in the low concentration range (1.67×10⁻¹¹~3.3×10⁻⁹ mol·L⁻¹) and high concentration range (1.0×10⁻⁸~3.3×10⁻⁶ mol·L⁻¹). The anti-interference experiment results show that the co-existing inorganic ions and organic compounds found commonly in urine have no obvious effect on the detection, indicating the well selectivity of the method. The spiked results obtained in real urine samples exhibit a recovery ranged from 91.4% to 109.2%.