Novel hollow structure based on CuO modified V2O5 nano-string of pearls (V2O5/CuO NSPs) were synthesized via electrospinning technique. The achieved V2O5/CuO NSPs exhibit interesting shapes of string of pearls, endowed with transparent and hollow structure under TEM observation. The V2O5/CuO NSPs sensors demonstrated that the sensitivity (R-a/R-g = 8.8 at 500 ppm) towards acetone was 3.2 times as high as that of pristine V2O5 nanofibers (NFs) (R-a/R-g = 2.5 at 500 ppm) at 440 degrees C. The improved sensitivity may be ascribed to the formation of V2O5/CuO p-n heterojunctions at the interfaces, which elevates the barrier height and enlarges depleted electron region.