The mitigation of mechanical anisotropy is observed in 2:17 type SmCo magnets by adjusting the Zr content. This behavior is supposed to be closely related to the density of lamellar phase, the density of which is enhanced obviously with increasing Zr content. The other reasons which could cause the reduction of the mechanical anisotropy is discussed from the Zr-rich impurity phase to the atom sub-stitutions and crystal lattice distortion. The observation of crack in nanoscale that clearly forms angles of 60° and 90° with respect to the lamellar phase, indicates that the probable cleavage planes are crystal faces (1011) and (1010). The results of investigation can deepen the understanding of mechanical anisotropy and cleavage fracture in the SmCo magnets.