Ultrafine fish bone powder (UFBP) from silver carp (Hypophthalmichthys moli trix) was prepared using dry media milling. The characteristics of UFBP were investigated by a laser particle size analyzer, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), and inductively coupled plasma (ICP) spectrometry. The size and specific surface area of UFBP particles were significantly (p < 0.05) affected by rotation speed, media/powder weight ratio, media diameter, and milling time. With the following conditions: rotation speed of 400 revolutions per minute, ratio of media to fish bone powder at 4:1, media diameter of 2 mm and 2.5 h of milling time, the optimal values of particle size (1.75 μm) and specific surface area (7.75 m²/g) were obtained. The SEM results confirmed that the particle became smaller and more uniform after milling treatment. Ash (63.71%) and protein (20.52%) were the main components of UFBP, and total calcium content was determined to be 236.90 mg/g in dried UFBP. As UFBP particle size decreased, calcium solubility significantly increased (p < 0.05), calcium content on the surface layer decreased, but the chemical compositions and structure did not change.