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<jats:title>Abstract</jats:title> <jats:p>The crystal structure, magnetization, and spontaneous magnetostriction of ferromagnetic Laves phase GdFe<jats:sub>2</jats:sub> compound have been investigated. High resolution synchrotron x-ray diffraction (XRD) analysis shows that GdFe<jats:sub>2</jats:sub> has a lower cubic symmetry with easy magnetization direction (EMD) along [100] below Curie temperature <jats:italic>T</jats:italic> <jats:sub>C</jats:sub>. The replacement of Gd with a small amount of Tb changes the EMD to [111]. The Curie temperature decreases while the field dependence of the saturation magnetization (<jats:italic>M</jats:italic> <jats:sub>s</jats:sub>) measured in temperature range 5–300 K varies with increasing Tb concentration. Coercivity <jats:italic>H</jats:italic> <jats:sub>c</jats:sub> increases with increasing Tb concentration and decays exponentially as temperature increases. The anisotropy in GdFe<jats:sub>2</jats:sub> is so weak that some of the rare-earth substitution plays an important role in determining the easy direction of magnetization in GdFe<jats:sub>2</jats:sub>. The calculated magnetostrictive constant <jats:italic>λ</jats:italic> <jats:sub>100</jats:sub> shows a small value of 37×10<jats:sup>−6</jats:sup>. This value agrees well with experimental data 30×10<jats:sup>−6</jats:sup>. Under a relatively small magnetic field, GdFe<jats:sub>2</jats:sub> exhibits a V-shaped positive magnetostriction curve. When the field is further increased, the crystal exhibits a negative magnetostriction curve. This phenomenon has been discussed in term of magnetic domain switching. Furthermore, magnetostriction increases with increasing Tb concentration. Our work leads to a simple and unified mesoscopic explanation for magnetostriction in ferromagnets. It may also provide insight for developing novel functional materials.</jats:p>