We are developing, at the Huazhong University of Science and Technology, a small-animal positron emission tomograph (PET) scanner that has two new features. Firstly, it uses detector modules that are based on a new digital readout electronics previously investigated and reported by us. Secondly, it can arrange the detector modules into various scanner geometries for different imaging needs. In this paper, we will describe the design and implementation of the detector module and report its performance properties. The detector module has a total detection sensitive area of 5.3 × 5.3 cm ² , an overall energy resolution of 14.1% FWHM at 511 keV, and a block-level coincidence timing resolution of 1.5 ns FWHM. In addition, our preliminary imaging study shows that our small-animal PET scanner can resolve 1.0 mm-diameter rods separated by 2.0 mm.