ZnO thin films were deposited on polyimide foil substrates using cathodic vacuum arc deposition technique. X-ray diffraction was used to investigate the influence of bias voltage on the structure of ZnO thin films. The results show that all the samples have (002) preferred orientation. The internal stress of the films is compressive stress which increases with the bias voltage. Fragmentation test shows that the intrinsic interfacial shear strength of ZnO thin film without bias voltage is slightly lower than the shear yield strength of polyimide substrate; the intrinsic interfacial shear strength of ZnO thin film increases with the bias voltage from -50V to -200V, which indicates that bias voltage is beneficial to the enhancement of the adhesion between ZnO films and polyimide substrates. Further increase of the bias voltage to -300V leads to surface damage of the polyimide substrates.