This work is devoted to the study of the magnetic domain structure (DS) in heterogeneous nanocrystalline alloys (R,Zr)(Co,Cu,Fe)z (R = Sm; z = 6.0-6.7). The methods of optical and atomic force microscopy were used to determine the parameters of micro- and nanostructure («cells») of the alloys. The method of magnetic force microscopy was used to obtain the images of the domain structure of these samples. A comparative analysis of the parameters of the domain and "cellular" structure of the alloys was performed. The dependence of the DS parameters on the parameters of the nanostructure is shown. The mixed mechanism of the magnetic reversal realized in these alloys is discussed.