We prepared oriented Co3+ doped M-type hexaferrites Sr0.5Ba0.5Fe12 – XCoXO19 (x = 0 – 1) with tunable anisotropy field. The magnetic properties of Sr0.5Ba0.5Fe12 – XCoXO19 with different Co3+ content were investigated. Results show that the particles of powder samples with different Co3+ content are aligned and have a similar hexagonal shape. The saturation magnetization increases firstly and then decrease with the increase in Co3+ content. The coercive field decrease sharply with little Co3+ content and then stand at a low level. Calculated magnetic anisotropy field show that substitution of Co3+ for Fe3+ can adjust the anisotropy filed from 21kOe to 15kOe. Furthermore, we also observed the sample changing from uniaxial anisotropy to plane anisotropy.