Nano β-Cu(copper β-resorcylate) were prepared via a facile wet mechanical grinding method, and were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Meanwhile, the catalytic properties of nano β-Cu were investigated. Results reveal that the nano β-Cu is semi-spherical and homogeneous with a fairly uniform size of 100 nm. DSC results show that the nano β-Cu has significant catalytic effects on ultra-fine AP with different particle size. The peak temperature of decomposition in the high temperature range for 6 μm and 1 μm AP decreases to 373.1 ℃ and 351.2 ℃, respectively, and the apparent decomposition heat increases to 1529 J·g^-1 and 1513 J·g^-1, respectively. And the reaction rate constant increases about 10 times. Compared with 6 μm AP, nano β-Cu makes the peak temperature of the high temperature decomposition of 1 μm AP obviously lower, and the reaction rate constant much higher, indicating nano β-Cu exhibits much better catalytic efficiency for accelerating the thermal decomposition of 1 μm AP.