Mid-infrared (IR) detectors based on the emerging low-dimensional (two-dimensional and quasi one-dimensional) materials offer unique characteristics including large bandgap tunability, optical polarization sensitivity and integrability with typical silicon process, which are not available in the mid-IR detectors based on traditional compound semiconductors. Here, we review the recent progress in study of mid-IR detectors based on the low-dimensional materials, including black phosphorus, black arsenic phosphorus, tellurene and BaTiS₃, from the perspectives of crystal structure, material synthesis, optical properties, and the detector characteristics. The detector gain and detectivity are benchmarked, and the unique properties, such as the polarization sensitivity, are discussed. We also provide our perspective about key future research directions in this field.