The orthogonal experiment and microstructure observation of single-pass equal channel angular extrusion（ECAE）7075alloy were carried out.The experimental results indicate that the grain refinement effect exhibits desirable by using ECAE die with 90°.Based on the Zener-Hollomon parameter model and the premise of the given initial average grain size 40μm

the numerical simulation of the microstructure evolution was preformed by the Deform-3Dsoftware with microstructure module to analyze the microstructure and the grain size in the different cross section.The simulated results reveal that the average grain sizes reach 3.5μm

2.4μm

29.1μm in the top

the middle and the bottom

respectively

exhibiting refinement to some extent

which is well agreement with the experimental ones.