In this paper, the microstructure of Co90Zr7Ta3 ternary alloy and the effect of microstructure on the PTF (pass through flux) were studied by means of metallographic observation, XRD analysis and PTF measurement. The influence of thermo mechanical treatment on the permeability was obtained by analyzing the structure and PTF of the material. The results show that the ternary alloy of Co90Zr7Ta3 prepared by vacuum melting mainly contains the precipitates of Co matrix and dendrite structure of (Co,Ta)11Zr2. After rolling and heat treatment, the dendrite structure in the alloy was broken to form dispersed precipitates. At the same time, the fcc phase in Co matrix is transformed into hcp phase, and the permeability of the target is improved by increasing the orientation of (0001) in hcp phase.