The wide bandgap of diamond, along with its extreme semiconductor properties, offers the promising route for deep-ultraviolet (DUV) detection, especially under solar-blind condition and harsh environments. The ideal photodetector should generally satisfy the 5S requirements such as high sensitivity, high signal-to-noise ratio, high spectral selectivity, high speed, and high stability. In this paper, we comprehensively investigate the DUV detectors fabricated from various kinds of single crystal diamonds such as boron-doped diamond homoepitaxial layer, intrinsic diamond homoepitaxial layers with different thicknesses, and single crystal diamond substrates. The post process such as hydrogen plasma treatment on the performance of the DUV detectors is also examined. The strategies to develop high-performance diamond DUV detectors are provided.