Sensitive X-ray detection is needed in diverse areas motivated by a common desire to reduce radiation dose. Cold cathode X-ray detectors operating with a photoelectron multiplication mechanism called electron bombardment induced photoconductivity (EBIPC) have emerged as promising candidates for low-dose X-ray detection. Herein, the cold cathode detectors formed by ZnO nanowire field emitters and β-Ga2O3 photoconductor targets were proposed for sensitive direct-conversion X-ray detection. The charge carrier transport mechanism of EBIPC effect in X-ray detectors was investigated to achieve a high internal gain (2.9×102) and high detection sensitivity (3.0×103μCGyair-1cm-2) for a 6 keV X-ray at the electric field of 22.5Vμm-1. Furthermore, the proposed X-ray detectors showed the features of fast response time (40 ms), long-term stability (0.6% for 1 h), and low detection limit (0.28mGyairs-1), suggesting that the direct-conversion cold cathode X-ray detectors are ideal candidates for low-energy X-ray detecting and imaging applications.