Diamond is a highly suitable material for X-ray detectors that can function effectively in harsh environments due to its unique properties such as ultrawide bandgap, high radiation resistance, excellent carrier mobility as well as remarkable chemical and thermal stability. However, the sensitivity of diamond X-ray detectors needs further improvement due to the relatively low X-ray absorption efficiency of diamond, and the exploration of single-crystal diamond array imaging still remains unexplored. In the current work, a 10 × 10 X-ray photodetector array was constructed from single-crystal diamond. To improve the sensitivity of the diamond X-ray detector, an asymmetric sandwich electrode structure was utilized. Additionally, trenches were created through laser cutting to prevent crosstalk between adjacent pixels. The diamond X-ray detector array exhibits exceptional performance, including a low detection limit of 4.9 nGy s^-1, a sensitivity of 14.3 mC Gy^-1 cm^-2, and a light-dark current ratio of 18,312, which are among the most favorable values ever reported for diamond X-ray detectors. Furthermore, these diamond X-ray detectors can operate at high temperatures up to 450 °C, making them suitable for development in harsh environments.