Copper beta-resorcylate (cupric 2,4-dihydroxy-benzoate, beta-Cu) nanoparticles were prepared at a large-scale via a facile wet mechanical grinding method and vacuum freeze-drying process. The as-prepared beta-Cu nanoparticles were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FT-IR). The results revealed that the nano-sized beta-Cu is of semi-spherical shape and of homogeneous distribution, with a fairly uniform size of 100 nm. The formation mechanism of beta-Cu nanoparticles in the whole process was discussed in detail. Furthermore, the catalytic properties of as-obtained beta-Cu were investigated. The TG/DSC study showed that nano-sized beta-Cu could be a promising additive for accelerating the thermal decomposition of ammonium perchlorate (AP).