Abstract The structural and magnetic properties are important parameters for spintronic applications of Heusler compounds. The Co₂FeAl and CoFe₂Al alloys are considered as the representatives of the regular and inverse Heusler structure, respectively. Here, we present a systematic study of the structural and magnetic properties of Co_3−x Fe _x Al (x = 1 ∼ 2) Heusler thin films grown on MgO (001) substrates. The lattice parameters and magnetic properties, such as magnetic coercivity, saturated moment and four-fold magnetic anisotropy constant, display different change trends in the Co-rich and Fe-rich regions, which suggest that magnetic properties have relevance to the Heusler structures. Our findings give a better understanding of the Heusler structures and magnetic properties, which is helpful for developing spintronic applications.