The influence of ultrasonic ball milling (USBM) on the structure-phase characteristics and magnetic properties of ultrafine powders (UFPs) of Cu–Co and Cu–Fe alloys is investigated by X-ray analysis and magnetic methods. The UFPs are obtained by electric-spark method in different liquids. As shown, the USBM process of UFPs results in the decrease of the volume fractions of Co–Cu and $\alpha$-Fe–Cu ferromagnetic phases and in the increase of the amount of oxides. As also shown, the USBM leads to essential increase of the dispersion of all phase components for UFPs of two alloys and to the decrease of the cobalt and iron concentrations in the Co–Cu and $\alpha$-Fe–Cu solid solutions, respectively. After USBM, magnetic properties of UFPs are changing accordingly to the variations of their phase states and dispersion, viz. the specific saturations magnetization decreases from 60.3 to 14.6 A$\cdot$m$^2$/kg, coercive force increases from 0.15 to 28 kA/m, and residual magnetization increases from 16.2 tо 467 mТ. In a case of the USBM increasing, coercive force and residual magnetization pass through the maxima related to the transition to the one-domain state and further to superparamagnetic state. As assumed, the indicated structural-phase peculiarities are caused by the presence of the oxide or carbide shells on the particles’ surface. These shells are formed both during the UFPs production and during the USBM process. The estimation of the surface shells’ thickness shows its changes in the interval from 1.3 to 5.8 nm and its dependences on the size of ultrafine particles, the production conditions, and USBM duration.