Nanopowder of a magnetically hard material-strontium hexaferrite-has been synthesized using laser evaporation followed by annealing. The phase composition, magnetic properties, and dispersion characteristics of the nanopowder have been investigated. As was shown by electron microscopy studies, upon laser evaporation the powder particles have a regular spherical shape and the size of the main fraction is in the range of 5-50 nm. From the data of X-ray phase analysis, the synthesized powder contains a large amount of the amorphous phase, whereas magnetite (iron oxide) is the main crystalline component. From the data of magnetic measurements, the nanopowder has low saturation magnetization and there are no magnetically hard properties. The effect of thermal treatment on the nanopowder phase composition, dispersion, and magnetic properties has been studied. It has been demonstrated that heating up to 820°C results in the crystallization of the amorphous component of the nanopowder, which increases the ferrite phase content up to 90 wt %, and the material manifests magnetically hard. In this case the degree of dispersion decreases, but the powder remains nanosized.